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By John E. Trombly

System objectives and design criteria for an in-mine ULF radio paging system are discussed Coding formats, frequency and bandwidth selection criteria leading to the system design are discussed. The prototype call alert transmitter and pocket page receiver is functionally described. The report includes circuit descriptions, schematics, parts lists, printed circuit fabrication and assembly drawings. The report concludes with an estimate of the manufacturing cost for each assembly.

Jan 1, 2011

By Edward L. McHugh

The study area, which comprises 11,500 acres, includes the 9,610-acre Whitewater Wilderness Study Area, in the California Desert Conservation Area, 15 miles northwest of Palm Springs, CA. The U.S. Bureau of Mines evaluation of mineral resources is based on examination of prospects and mineralized areas during the spring of 1981. The Whitewater study area is mainly underlain by granodiorite to quartz diorite and their gneissic equivalents in an igneous-metamorphic complex. Late Tertiary sedimentary and volcanic rocks locally overlie the crystalline complex in the eastern part of the study area. The study area lies between branches of the San Andreas fault system.

Jan 1, 1986

By B. A. Osei

Research to evaluate possible metrics for predicting dredgeability of compact aggregates, by hydraulically actuated clamshell dredges, shows work done by the pistons as a viable metric. Analysis of field data shows that there is a low, positive, correlation between cycle time (CT) and work done. If this correlation exists, then CT has to be considered an independent variable affecting work done during dredgeability assessment. Further research is required to elucidate the relationship between CT and work done during dredging. The objective of this paper is to test the hypothesis that work done during dredging increases with increasing CT. Kinematics and dynamics of the hydraulic clamshell were modeled and implemented in Simulink® in MATLAB. The model was validated using field data. The model was then used to test the research hypothesis. The results show that work done increases with increasing CT. This work confirms that work done during dredging increases with increasing CT. This result indicates that though an operator can increase the CT to deal with difficult digging, inputting unduly high CTs results in higher energy consumption during dredging.

Jan 1, 2011

By V. L. Andrade, K. L. C. Goncalves, N. A. Santos

This paper describes results obtained in a test program performed with new equipment, called Mini Pilot Plant, manufactured by Canadian Process Technologies. This equipment was acquired by CVRD aiming at testing flotation circuits, in a continuous closed configuration, with samples obtained from drill cores. Success of this goal would allow CVRD to establish the metallurgical performance of mineral deposits with more confidence in comparison to Locked Cycle Tests (LCT). This paper discusses the importance of assessing the ore variability and compares results obtained in LCTs and Mini Pilot Plant. Results suggest that more reliable data is obtained in MPP test.

Jan 1, 2002

By P. A. Hagerty

Biological treatment of metals-impacted water using sulfate reduction is a viable means of treatment that has been applied in pilot and full scale at numerous projects. One of the fundamental challenges with this type of treatment is the selection of an appropriate substrate to support the sulfate reduction process long-term. The substrate degradation products provide a carbon source and an electron donor for metabolism by sulfate-reducing bacteria and consequently organic characteristics are critical; however, the physical attributes of the substrate are equally critical to an efficient and optimized substrate mix. This paper explores the affect of particle size (a.k.a. grain size) of several substrate mixes on the treatment efficiency of sulfate reducing treatment systems. Substrate selection can be separated into two phases of evaluation, the primary selection phase and the secondary optimization phase. The primary selection phase considers such fundamental attributes as source availability, economics, bioavailability and longevity. These fundamental activities are conducted in order to identify potential candidate ingredients of the substrate mix which are regionally available, economically viable and consistent with the biogeochemical aspects of the project. Recent work has been conducted in the development of testing protocol for organic substrates to quantify bioavailability (Martinez Hernandez et al. 2010, Place et al. 2006) as part of the primary selection phase. Once the substrate ingredients have been selected based on the primary criteria, the mixture of these ingredients is then developed based on an optimization process, including consideration of the substrate ingredient?s particle size distribution.

Jan 1, 2011

FOR many years past it has been the practice at the Bairnsdale School of Mines to treat any parcels of auriferous concentrates sent in from the surrounding district by roasting them in a handworked reverberatory, and then chlorinating or cyaniding the product. According to Donald CIark, who has done a large amount of work on these ores, the results obtained were fairly satisfactory extractions of over 90 per cent being claimed. With some modifications, the method has been very generally adopted, not only in Gippsland but throughout Victoria. It is, however, difficult to get exact information as to the extractions actually obtained, and unfortunately no records of working results have been kept at the Bairnsdale School of Mines.Having treated several lots of ore by this method during 1907 and 1908 with unsatisfactory results, the writers thought it desirable to make a detailed investigation on some particular ore, both in the laboratory and on a working scale. The ore selectedwas a parcel of low-grade concentrates from Stirling, a small mining field situated about forty miles to the east of Bairnsdale. This ore was chosen chiefly on account of the heavy and inexplicable volatilization loss which took place even on roasting with the greatest care; the loss amounting to between 10 and 15 per cent. In the experiments here related, three main objects were kept in view:-1. To determine with what mineral 01' minerals the gold and silver were associated...

Jan 1, 1909

By G. C. Sun

Rock mechanics properties, i.e. uniaxial and triaxial compressive strength, indirect tensile strength shear strength, Young's modulus, and poisson's ratio were collected for coal and related strata from 50 coal seams in 90 mines. The methodology of data organization and retrieval is described in details. The values and .ranges of those properties are also discussed.

Jan 1, 1993

By R. B. Scott, J. Hewitson

The paper investigates the historical information relating to spontaneous heatings which have occurred within the area from 1955 to date. From this information the seams most liable are identified and the location within the workings is enumerated, together with the possible reason for the occurrence of the heatings. Details are given of the precautions taken during development, working and withdrawal. Sampling procedures are outlined and the interpretation of the results is discussed. Reference is made to the various types of material and techniques employed in both preventing and combating heatings and examples are given of their relative cost and the operational experience obtained. Special observations are made on the changes in mining techniques and their influence on spontaneous combustion.

May 23, 1905

In Broken Hill, Northern Rhodesia, two water jacket lead furnaces have been in operation for the past three years. The furnaces were erected in war time, and only absolute essentials were procurable. The water for the jackets was obtained from wells adjacent to the works, in a dolomite formation. There being no water-softening plant, except a small one capable of treating water for the power plant only, this water was found to make a heavy scale in the jacket. During 1917 several jackets were burnt through, resulting in serious trouble and loss of output. In order to avoid this, furnaces were stopped twice a month for 8 hours and scale was removed as far as possible. In addition to the scale trouble during the summer months, a green slime grew in the supply tanks and occasionally became detached from the tank and collected in the cocks near the jackets. This caused risk to the jackets and was difficult to remove without a stoppage of the furnace. In 1918, bundles of wattle bark were placed in the hot well at the rate of one ton per month. These extracted the tannin and added from 0.5 to one part of tannin per 100,000 to the circulating water. The hot water was cooled over a brushwood cooling tower and returned to the supply tanks. The well water required to, make up the wastage was estimated at 40,000 gal per day.

Jan 1, 1920

By Lloyd M. English

During the past 30 years, the research arena has changed significantly in all fields, mining included. The relative representation of the topics of research, how the research is performed and who has performed the research have all changed. Although there are a lot of subjective ideas and anecdotal "analyses" concerning these changes, there has been no actual study of these trends to verify the facts. This study was divided into six five-¬year periods for the purposes of comparison. Some of the trends analyzed are co-authorship, research areas, research sponsors and cooperative efforts. In today's research arena, 30 years is a long time. Technology has advanced more rapidly than in any time previously and that pace continues to increase. There are more researchers, more tools for research and an increasing number of companies, agencies and institutions engaged in research. The pace of change and its impact is often discussed and debated at professional meetings and in institutions that engage in research. These conversations will often influence the research decisions of the participants in directions to take or subjects to pursue.

Jan 1, 1995

By J. P. Neumann, L. Raymond

At temperatures near 1000°C, only the (112) (111) slip systems are operatire in tungsten. Therefore, the substructure introduced into the billet upon rleforming a single crystal by rolling at 1000 "C can be controlled by proper selection 01. processing ral'iubles. Using a reduction of 10 pct pel- pass, the (001)[110] and the (110)[001] crystals will deform by duplex slip rip to a 50 pet reduction in thickuess. These rolled single-crystal sheels are characlerized by anisotropic hardening, retention of ductility with warm working, lattice bending which is related to the conlacl (angle, and macroscopic dimensional changecs in the length bid not the width of the billet. When several slip systems become operative, a greater degree of work hardening is itztvoducetl into the crystal. This rolling- condition is characlerized by isotropic hardening, loss of ductilily with warm working, complex lattice distortions, and macro-scopic dimensional changes in both the length rind Width of the billel. IN tungsten, the {1 10}(111) slip systems are operative below room temperature,' while above 700°C only the {112{ (111) slip systems are observed.2,3 In the transition region, i.e., room temperature. both systems appear. It is the purpose of this investigation to show that tungsten single crystals deformed by rolling at a temperature where only one slip system is operative generate dislocation substructure which depends on the crystal orientation. For a specific crystal orientation. the resulting dislocation substructure can be further influenced by modifying the rolling procedure. Crystals oriented for multiple slip display less substructural sensi- tivity to modifications in processing techniques than do single crystals oriented for duplex slip. Under simple slip modes of deformation, very little work hardening is introduced into a rolled single-crystal sheet. Mechanical properties such as room-temperature strength. ductility, and hardness are used to confirm the existence of the different work-hardened conditions generated within the crystal by modified warm-rolling techniques. EXPERIMENTAL PROCEDURE Material. Single-crystal billets of four different crystal orientations. grown by the Arc-Verneuil technique. were ground to a size of 0.25 by 0.375 by 3 in. In terms of their rolling plane and rolling direction, the billets had the following orientations: (1101 [001 ] (110) [110] (001) [110] (001) [100] The actual orientation of all crystals was within 5 deg of the ideal orientations. The typical impurity content of the crystals is given in Table I. Polishing and Etching. Polishing was done elec-trolytically in a 20 g per liter aqueous solution of NaOH at approximately 10 v. It was established by the Laue back-reflection X-ray technique that the surface damage due to grinding and cutting operations with a diamond wheel did not exceed 0.001 in. Therefore after each cutting or grinding operation at least 0.002 in. was removed electrolytically from the surface in order to eliminate surface effects. By lowering the voltage to 3 v, subgrain boundaries and individual dislocations are identified in agreement with Berlec 4 where the etch-pit traces on a cubic plane form a square. The etching time was about 5 sec at room temperature. Rolling. Rolling was carried out on a Loma 2-high mill (Model 600). The peripheral velocity of the 6-in.-diameter rolls was 500 in. per min, with the surface temperature of the rolls about 400° to 450° C The billets were heated before each pass for 30 min in argon to 1000 C. Oxidation of the crystals during rolling in air resulted in a thin layer of greenish-yellow WO 3 This oxide was removed after each pass by immersing the crystals for a few minutes in a boiling NaOH solution. Prior to the initial rolling pass, a surface layer of 0.001 in. was removed by polishing. The crystals were then annealed in vacuum (10-4 torr) at 2400 C for 30 min. All crystals were rolled in the same direction; i.e., the same end was always introduced into the rolls. The rolling program was conducted in

Jan 1, 1965

Fluorspar was not mined in the United States during 2004, although a small amount of usable synthetic fluorspar (CaF2) was produced from industrial waste streams. The majority of fluorspar consumed in the United States came from imports or stockpiled material purchased from the National Defense Stockpile (NDS). In addition, consumption is supplemented by use of by-product fluorosilicic acid produced at phosphoric acid plants. In 2004, annual production of fluorosilicic acid was 50kt (55,000 st) or about 88 kt (97,000 st) of 92 percent fluorspar equivalent. In 2004, annual production of fluorosilicic acid was 50kt (55,000 st) or about 88 kt (97,000 st) of 92 percent fluorspar equivalent.

Jan 1, 2005

By P. A. Plunkert

Metallurgical-grade bauxite was imported into the United States from 11 countries in 2004. The principal suppliers of this 10 Mt (11 million st) of imported ore were Jamaica (33 percent), Brazil (25 percent), Guinea(23 percent) and Guyana (11 percent). The average value of imports, cost, insurance and freight (c.i.f.) U.S. ports, was $31/t ($28/st). Calcined refractory-grade bauxite imports were 165kt (182,000 st) with an average value of $146/t ($132/st), c.i.f. U.S. ports. China supplied 70 percent; Guyana, 22

Jan 1, 2005

By Daniel W. H. Su

The importance of incorporating fundamental principles of rock material response and failure mechanics into a pillar strength design model has been demonstrated. To accurately assess pillar strength, a model should account not only for the characteristics of the coal, but also for those of the surrounding strata. The interactions between the pillar and the surrounding roof and floor dictate ultimate pillar strength. Confinement, or the lack thereof, provided by roof and floor frictional end-constraint is one of the most significant factors in the strength of very wide pillars. The best conditions for end-constraint occur with ideally strong roof and floor. In this paper, it will be shown that weak roof and floor may decrease the ultimate pillar strength by as much as 30% compared to ideal conditions. Field observations confirm this pillar strength reduction in the presence of weak roof and floor. Furthermore, rock partings within the coal have a variable effect on pillar strength, depending on the parting strength. A competent shale parting within the coal reduces the effective pillar height, thus increasing the ultimate pillar strength; a weak claystone parting slightly decreases the strength. Imposed load distribution also has a significant effect on pillar strength, such that asymmetric pillar loading, similar to that observed in pillars adjacent to high extraction mining, reduces the ultimate pillar strength below that of equivalent pillars subject to uniform load distributions.

Jan 1, 1997

By S. McCalpine, W. Muir, P. J. Downey

"Golden Bear Operating Company Ltd. (GBOC) was a joint venture between Chevron Minerals Ltd. and North American Metals Corp. that was formed for the development of the Golden Bear Project. The mine is located at Muddy Lake, Western British Columbia, approximately 80 km northwest of Telegraph Creek and 135 km west of Dease Lake (see Figure 1). Road access to the mine was developed by Golden Bear and consists of a radio controlled 155 km gravel road originating at highway 114.A feasibility study was completed in 1987 and project approval was finalized in 1988 with Golden Bear issuing a ""Request For Proposal"" for detailed engineering in May 1988. Golden Bear also commenced negotiating with vendors at this time for the supply of the two principal process equipment packages: the dry grinding and classification system and the whole ore roaster package.Process plant engineering and plant construction was completed in October 1989 with plant startup commencing in November 1989. Two months into the commissioning phase it became apparent that the plant, as designed, would not achieve the anticipated production targets.Kilborn Engineering Pacific were subsequently contracted by GBOC to review and modify the plant design, assist the operating personnel with plant commissioning and startup and provide operator training.This Paper describes some of the problems encountered during the startup and the plant modifications incorporated to achieve design parameters."

Jan 1, 1992

By Osama El-Fiky

There are many types of deep foundations currently being used in the San Francisco Bay Area, one of the most common being driven precast, prestressed concrete (PC/PS) piles. PC/PS piles are frequently selected for use due to of ease of installation, availability, and relatively low cost. Disadvantages of using PC/PS piles are noise, vibrations, pollution, front-end delays due to indicator pile programs, and reduced flexibility. An acceptable alternative to driven PC/PS piles was selected for construction of foundations for the heavy housing and administrative buildings at the San Francisco County Jail #3 replacement project in San Bruno, California. The pile type selected, the Auger Pressure Grouted Displacement (APGD) pile, was chosen to reduce noise, vibrations, installation time, and cost, and to allow for greater flexibility of installed pile lengths. This paper presents a case history of the use of APGD piles that were substituted for driven PC/PS concrete piles for the subject project. Standard and quick loading pile load tests were performed to confirm adherence with the design criteria originally used for the driven PC/PS concrete piles. The APGD piles were found to increase shear strength around the piles similarly to driven displacement piles. In addition, this paper presents the methodology used in monitoring APGD pile installation.

Jan 1, 2002

By David A. Summers

The use of high pressure fluid cavitation is investigated as a means of breaking an ore into its constituent grains. This Cavitational Rock Dissagregation (CRD) is found to be possible and effective in breaking down galena ore, both in sandstone and dolomite host material. The technique did not work as well in comminuting and cleaning oil shale, because the cavitation drove the oil into emulsion with the water. The presence of dominant bedding in the rock also caused preferential breakage to these lines, rather than to the individual grain boundaries. This problem was also encountered in tests on igneous ore where weakness plants of the overall ore proved weaker than the boundaries of the individual grains. It was found that the prevailing expression of cavitation erosion dependence on pressure was not absolutely valid. In contrast it was found that CRD is much more sensitive to jet flow diameter, and when this was recognized it was found possible to erode rock with compressive strength of up to 350 MPa with operating jet pressures of 10 MPa.

Jan 1, 1982

By P. Sanchez-Mejorada

GEOLOGISTS who are acquainted with the mines of northeastern Mexico realize that the most important lead-silver replacement deposits of the province are confined to a single formation. But since the formation is several hundred meters thick, the author has determined the relative position of the lead mantos in the belief that this information will prove useful in the search for new mines. This article describes the stratigraphic location of lead-silver replacement deposits known in several mines situated in a region comprising part of the states of Coahuila and Nuevo Leon. The area studied extends for 200 km* (125 miles) from east to west and 70 km (45 miles) north to south. Metallogenic Province: The most important metallic deposits of the region have the following common characteristics: 1) The orebodies occur as manto replacements of calcareous sediments. 2) The horizons that have contributed large tonnages of ore are in similar positions in the corresponding stratigraphic columns (as it will be shown later on). 3) Lead is the most important metal in the ores. Silver is commonly present in small amounts. Occurrence of zinc is dependent on the degree of oxidation of the primary sulfides. 4) A large proportion of the total production has been in the form of oxidized ores. 5) The deposits are located on anticlines. Rocks of Cretaceous age crop out over large areas of the states of Nuevo Leon and Coahuila. forming part of a belt that extends to the south along the eastern Sierra Madre. The sediments are cut by a small number of intrusive stocks ranging in characteristics from rhyolite to diorite. The most prominent structural feature of the region is a series of folds trending northwest-southeast. Faulting is not conspicuous in the region, although a major fault zone is found farther East.' The physiography closely reflects structural features, with mountains formed by anticlines and valleys conforming with intermediate synclines. Narrow valleys have also been developed along the axes of many anticlines, where solution of limy sedi- ments and erosion have proceeded along axial tension fractures. Stratigraphy: Rocks of the Upper Cretaceous are exposed in only a small percentage of the total area. Generally they have been eroded away from the mountains and are covered by recent talus and alluvium in the valleys. Humphrey' has published an excellent paper describing the Cretaceous formations of the Sierra de los Muertos, a short distance west of Monterrey. A brief summary of these formations is given below to convey an overall picture of the stratigraphic sequence that prevails just south of the area under consideration. Upper Cretaceous Indidura: Essentially thin shaly sediments. Cuesta del Cura: Limestone in thin wavy beds

Jan 1, 1959

By H. F. Silliman, Daniel R. Hull, Earl W. Palmer

THE brass-rolling industry has not had a great deal of experience with antimony in its product. There have been some recent excursions with antimony as a corrosion inhibitor in tubes, but in sheet brass it has been regarded with apprehension and generally avoided. This is not to say that [ ] contaminations have never occurred, and probably a great many brass mill men have had their own ideas on the effect of such contamination. Our own views were based upon certain experiences some years ago with strip castings that split lengthwise in the early stages of rolling. The nature of this splitting is shown in Fig. I, from a photograph taken in 1922 as a record of 20 bars of 65-35 common brass made with an antimonial brand of copper. These bars were cast 6 ¾ in. wide by 1 in. thick by 45 in. long. In the first pass through the rolls, 19 of the 20 split lengthwise throughout their length, while each half curved outward in a wide arc as it emerged from the rolls. [ ] In those days, if splitting was not a frequent occurrence, it was not unfamiliar. One can recall periods of short duration when large amounts of common brass would behave in this way. There was nothing imaginary about these spells. The affected metal would split lengthwise in the breaking rolls, and no maneuvering of mill practice made any difference. The condition would descend like a plague, demoralize the mill for several days, and disappear. It is doubtful if anyone knew the cause-however many explanations may have been current. In 1921 a quantity of split brass was traced to the use of fired small-arms

Jan 1, 1943

"IntroductionThe combined library facilities of the five universities in the Generic Technology Center for Respirable Dust, The Pennsylvania State University, West Virginia University, University of Minnesota, Massachusetts Institute of Technology, and Michigan Technological University, represent one of the most extensive and comprehensive collections of information on respirable dust research which is available in the United States. The Center encompasses two major medical schools, the Milton S. Hershey Medical Center at The Pennsylvania State University and .West Virginia University Hospital at West Virginia University, and includes national and international experts from such diverse disciplines as geology, geomechanics, mining engineering, mineral processing, electrical engineering, industrial engineering, mechanical engineering, material science, physics and several areas of medicine. In order to maximize achievements in research and facilitate early results application in the private industry, university, government and public sectors, a geographically dispersed Reference Center on Respirable Dust has been established at each of the affiliated universities. This network serves to encourage unity between the universities in the Center and coordination and communication with other entities who benefit from their research.Description of the Reference CenterIn this light, the goal of the Reference Center network is to identify at what location Information is available and to provide a means for others to access this information. It is especially necessary to have both ease of input and maximum retrieval capabilities available to all the research personnel in the Reference Center. At the same time, the service provided to the inquiring public must be complete and cost-effective. The Center's approach to realizing this goal incorporates advances in computerized and electronic searching of individual library holdings and the networking of major library and commercial search systems.The Reference Center uses the following means to achieve this goal. At each participating university, a hard copy collection ls maintained of the current respirable dust research in progress by that institution's personnel. Also, available. at each university ls a review of their past and present research on respirable dust. At each participating university a hard copy collection of annual status reports and of all publications produced by Center personnel for symposiums, national and international conferences ls maintained. A key word computer search capability ls available to participating universities. This computer search, by title, author and location, allows researchers to determine at which facility information is available, thus avoiding the tremendous expense and effort of housing all the information on respirable dust research under one roof. The Reference Center has access, through The Pennsylvania State University Libraries system and the libraries of other institutions, to a large number of data bases such as MEDLINE at the National Library of Medicine,"

Aug 31, 1989