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By John H. Raymer

The accuracy of inflow estimates depends largely on how well permeability is characterized. Permeability is best evaluated as a statistical distribution. For the Chattahoochee Tunnel, this distribution was obtained with a large number of packer tests performed in 50 boreholes along the alignment. The distribution of packer-test data may not accurately reflect permeability, however, due to the limits of the test method and the luck of the field investigation. These discrepancies may be overcome by using log-normal plots of the data to develop a permeability model that will be use din lieu of the data to calculate inflow.

Jan 1, 2001

By G. V. Sullivan, B. E. Davis, T. O. Liewellyn

A technique was devised by the US Bureau of Mines to recover coarse [+1.2-mm (14- mesh)] North Carolina phosphate now discarded as waste. Concentration utilizes the difference in particle sphericity between the relatively flat calcite and the rounded phosphate pebbles. Sizing, treatment in a continuous hydraulic classification system, and grinding upgraded a 17% P,O5 reject to 4.5% P,05 with a phosphate recovery of 63%. The CaO: P2O5 ratio was reduced from 2.49 to 1.66.

Jan 1, 1987

By M. G. Yalçin

Marbles commercially known as the Nigde- white crop out in the town of Gümü?ler, around the Çalkama Hill within the Gümü?ler Formation of the Nigde Masif of Paleozoic age. Marbles sporadically occur within the masif, however its prevalent occurrence is associated with the Gümü?ler Formation. Due mainly to its intense fractured nature, the Nigde-white marbles are used as dimension stones, crushed stones and most recently micronized calcite. Insignificant portion accounts for block use through a few quarries.

Jan 1, 2005

By John C. Edwards, Robert C. Bates

Modeling uranium mine radiation control methods and natural environmental radon variations is an extremely complex endeavor. A number of authors have examined particular facets of the problem and have proposed models for their area of interest. Bureau of Mines personnel brought together many of these individual studies, and from them have attempted to develop a coordinated plan for modeling radon daughter concentrations in the uranium mine environment. This approach is described.

Jan 1, 1981

By R. Codell, D. L. Hughson

The authors benchmarked the integrated finite-volume code MULTIFLO against the analytical solution of Philip et al. (1989) for cylindrical underground openings. They found that the numerical simulation of dripping threshold flux was consistently higher than the analytical solution for rectangular and unstructured grids. The magnitude of this error was proportional to the alpha parameter characterizing capillarity. This error may bias estimates of seepage into drifts for repository performance towards nonconservatism.

Jan 1, 2002

By John K. Kellis, Fazley Azhar

Advancements in AC drive technology offer conveyor designers a viable drive alternative for conveyor systems which require accurate load sharing as well as multiple drive systems. Recently developed AC drives have the ability to accurately control the output torque of AC motor. These AC drives, compared to current DC drives, offer superior performance characteristics while enjoying the benefits of an AC motor. Conveyor applications and case studies incorporating this AC drive technology are presented for review.

Jan 1, 1998

By John A. Christophersen, Adolf J. Jonaitis

Coal flotation applications utilizing column flotation have been shown to improve grade and recovery when compared with traditional mechanical cell flotation. Deister Flotaire Column Flotation Machines have been installed in pilot and commercial coal cleaning applications. Comparative data covering prior and current flotation is presented. In addition, special characteristics covering the Deister air generation system are presented.

Jan 1, 1989

By A. Filyk, R. Woods

The current plant practice at Molycorp, Inc., Questa Division, a molybdenum producer in northern New Mexico, is described. An outline of crushing, grinding, flotation, drying, and tailings disposal is included, with emphasis on metallurgy.

Jan 1, 1976

By I. Tsolas

This paper presents the use of the Jaggi-Freedman model for deriving composite environmental sustainability indicators at the mine level (i.e. indicators which focus on both the environmental and economic dimension of the sustainable development) using environmental, economic and/or integrated indicators (i.e. indicators which inter-relate two dimensions of sustainability). The derivation of composite environmental sustainability indicators by means of the Jaggi-Freedman model concerns the South-Field lignite mine of Public Power Corporation (PPC) in Western Macedonia. In the light of the results of the present paper it is evident that the performance of South-Field mine, during 1986-1990, was the exclusive domain of large production yearly activities. The considerably low indicators? scores during the 1986-1987 period are attributed to the increased environmental impacts and electrical energy consumed. The merit of this framework is that it can be used both internally, for benchmarking purposes and externally, for sustainability reporting.

Jan 1, 2006

By Clifford J. Lewis

The role of calcareous minerals in that area of the environmental improvement program involving the control or elimination of sulfur oxide emissions is discussed, and a new concept in gas scrubbing, rendering possible the use of calcareous rocks more extensively for this purpose, is presented. Calcareous rocks are defined as the more common limestones, consisting essentially of calcium carbonate and magnesium carbonate. The effect of magnesium carbonate on the reaction rate of limestones and lime toward sulfur oxides in aqueous scrubbing systems is pointed out. The relative economics of lime- stone versus lime as aqueous scrubbing reagents for sulfur dioxide are indicated.

Jan 1, 1974

By J. A. Finch, B. J. Huls

Accurate level detection is required to make full use of level in optimizing control strategies for flotation columns. Techniques based on pressure and electrical conductivity are compared. Pressure and conductivity profiles give good agreement on level. Level calculated from single and multiple pressure values became more accurate using, in order, one, two and three sensor locations. The level estimate remained in error, however, because, unlike the collection zone, froth zone bulk density varies with height. A conductivity probe continually updating the conductance profile is a practical method of obtaining an accurate level.

Jan 1, 1990

By John N. Murphy, Edward F. Fries

The availability of fast, low-cost computer hardware and advanced software is opening new opportunities for minerals extraction and processing. Programmable Logic Controllers (PLC's) are currently used extensively in the minerals industries; this paper looks beyond PLC's and that vintage of “computer control”--it looks toward what the authors see as new in the next five years. Topics covered include expert systems, neural networks, intelligent signal processing, and hierarchical controllers as applied to mining and mineral processing operations.

Jan 1, 1993

By Shawn Benner, David Blowes, Carol Ptacek

A full-scale reactive barrier was installed into an aquifer impacted by acid mine drainage in August 1995 at the Nickel Rim mine site near Sudbury, Ontario. The primary mechanism of water quality improvement is bacterially mediated sulfate reduction and metal sulfide precipitation. Dramatic changes in the groundwater chemistry are observed with up to 90% decline in Fe (from >18 to <2 mmol L-1) and increases in alkalinity from <1 to >10 mmol L-1 (as CaCO3). Over a 3 year period, the rate of Fe removal declines by approximately 35%. Primary controls on barrier performance are organic carbon reactivity, groundwater temperature, and variable residence time within the barrier.

Jan 1, 2000

By S. Michael Feroz, Paul Gribbon, Jan Rosholt

Approximately six billion gallons of combined sewage are discharged annually into Willamette River and Columbia Slough through Portland’s combined sewer system. The Columbia Slough Consolidation Conduit (CSCC) is an important element of mandated Combined Sewer Overflow (CSO) abatement. It includes2,548m (8,361 ft.) of 3.7 m. (12 ft.) internal diameter tunnel. The CSCC alignment traverses the UP railroad, Columbia Boulevard and parallels an old sewer. Geologic conditions include river alluvium and fine to coarse-grained flood deposits containing cobbles and boulders. This paper describes design and construction of a tunnel in soft-ground, with shallow cover and close to an old concrete sewer.

Jan 1, 1999

By H. Reginald Hardy, Maochen Ge

Data analysis is one of the most important steps required for the successful application of the acoustic emission/ microseismic (AE/MS) technique. A dedicated computer software package to analyze acoustic emission/ microseismic data associated with field applications in the geotechnical area has been developed recently at Penn State University. This paper addresses the major features and applications of this computer software package.

Jan 1, 1986

By R. P. Killmeyer, R. E. Hucko, P. S. Jacobsen

Cleaning of three coals from the eastern US was tested by five selective agglomeration processes and one selective flocculation process. The coals and processes are described, and the results are reported and compared. Two of the processes, which ground the coal to the finest volume mean diameter, met the stringent test program quality specifications.

Jan 1, 1991

By Victor F. Hollister

The Society for Mining, Metallurgy, and Exploration has compiled a number of exploration discovery case histories. This section in Volume 3 of the series describes the case histories of deposits found in layered rocks. Metallic and nonmetallic ore deposits described in this section include diverse minerals such as copper-nickel sulfides and carbonate-controlled base metals. Other case history compilations include epithermal precious metal deposits and porphyry systems. The importance of ores in layered rocks justifies their inclusion in a case history compilation. Mineral deposits occurring in layered rocks form an economically important class of ores. For example, most sulfide nickel ores are mined from basic layered intrusive rocks. Although the geologic setting is completely different from economic nickel sulfide concentrations, most barite produced also comes from stratiform and strata-bound ores. Zinc and lead ores importantly occur in beds in carbonate host rocks. Gold and other heavy minerals are concentrated in placer deposits. Indeed, the world&apos;s largest gold deposit, the Witwatersrand, is a fossil placer.

Jan 1, 1991

By Li Honggui, Liu Maosheng, Zhao Zhongwei, Sun Peimci, Li Yunjiao

Leaching of Shizhuyuan low-grade refractory tungsten ore was carried out in a mechanically activating reactor. The effect of experimental parameters-temperature, amount of Na2C03, addition of NaOH, ratio of liquid to solid and leaching time - on the recovery of WO3 was studied. The WO3 recovery up to 96.99% have been achieved when the tungsten ore was digested by soda not more than three times the stoichiometric amount at 185-195°C for 1 .O-2.0 hours. Iso-extraction countour diagrams were drawn to illustrate the effect of various parameters on leaching. The WO3 recovery could be expected to increase 10-15% compared to that of conventional soda autoclave process.

Jan 1, 1995

By G. W. Heunisch

The properties of Neutra-Fix® and Neutra-Ment®, two new lime substitutes for treating acid mine drainage (AMD), have been compared with lime and Allcament®, two products presently in use for AMD treatment. The two new products are basically dolomitic byproducts and produce sludges that are more compact than those from lime. Sludge settling rates are faster than lime with iron concentrations after 24 hours that comply with Environmental Protection Agency (EPA) regulations. Material utilization and optimum pH are reported.

Jan 1, 1988

By M. R. Leonard

It is estimated that between 5 and 15 pounds of solid waste are generated monthly by each individual. Finding a final resting spot for such waste is an important matter. In the "good ole days," dumps of every description and condition were available. Not so now. Almost all states have adopted and are enforcing strict regulations regarding the disposition of solid waste. Many companies, owing to the nature of their business, have potentially good waste-disposal sites available. Cleveland Quarries Company falls in this group; but in spite of our having state and county permits, opposition by the local community denied us the opportunity to provide a needed local service.

Jan 1, 1974