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By T. F. Witheree

The Fletcherville Furnace was built in 1864 and 1865, making its first blast from August until October of the latter year, when it was blown out to prevent its " bunging-up." Repairs were made in time to enable it to be blown in again December 12th, 1865, the blast ending October 7th, 1866. Total product 1921.15 tons iron, an average of 6.8.2.5 tons per day, from ores yielding 44.8 per cent. Consumption of charcoal 223.2 bushels per ton of iron. The furnace journal up to this time shows no record of furnace dimensions, or temperature of the blast, but as near as can be ascertained, they were as follows, viz.: Height of stack, 42 feet. Diameter of bosh, 11 feet. Angle of bosh, 71/2 inches to 12 inches rise, about 58°. Diameter of open tunnel head, 42 inches. Number of tuyeres 3 ; each 3 inches in diameter. Dam 15 inches high. Tuyeres 24 inches high. Tymp 224 inches high. Diameter of steam cylinder, 20) inches. } Diameter of blast cylinder, 64 inches. } Stroke 5 feet. The engine is direct-acting horizontal non-condensing. December 26th, 1866, the furnace was again put in blast, having been considerably altered in the crucible; the height of stack, bosh, and tunnel head remaining as before. Six tuyeres were put in, three in each of the side arches. The hearth or crucible was rectangular in form, 3 feet wide x 31/2 feet long x 64 feet high. Inclination of bosh 58°. Height of tuyeres 26 inches; nozzles 21/4 inches diameter. Temperature of blast estimated to be about 500°.

By I. T. Oramah

Despite the abundance of solid mineral deposits, Nigeria only earns about 0.5-1% of its current Gross Domestic Product (GDP) from the solid minerals sector. This is as a result of the dominance of the oil and gas industry, which has negatively affected the competitiveness of other sectors of Nigeria’s economy. The dominance of this industry has resulted in unemployment, poverty, hunger, domestic price inflation, corruption, unstable government, and higher exchange rates. These impacts are typical for economies suffering from the effects of "Dutch Disease" and the "Resource Curse". Community-based small-scale mining offers hope as an economic activity that can create wealth, employment, reduce hunger and poverty, and provide basic amenities for rural communities with solid minerals endowment. This study presents preliminary results of ongoing research into the prospects of using community-based small-scale mining in a developing country like Nigeria to move towards rural sustainable development.

Jan 1, 2011

By Alain Simard, André Gobeil, Sylvain Lacroix, Maurice Rive, Denis Racicot, Pierre Verpaelst

"The Abitibi volcano-plutonic belt forms the major portion of the Abitibi lithotectonic subprovince in the Superior Province. The Abitibi belt is composed essentially of"" (1) approximately 2.7 Ga old volcanic and sedimentary rocks; and (2) gabbro, tonalite, granodiorite and syenite intrusions occurring in well-defined prekinematic ( synvolcanic ), synkinematic and post-kinematic plutonic suites. Most of these rocks are metamorphosed to greenschist facies. Regional multi-phase deformation affects the volcano-sedimentary rocks. Deformation was initiated as these rocks were formed, and peaked at the end of the Keno ran orogeny with the emplacement of granitic batholiths.There are 145 former and current mines in the Quebec segment of the belt. To date, more than 420 Mt of ore have been extracted yielding 1,600 tonnesof Au, more than4,000 tonnesof Ag,4,400,000 tonnes of Cu and 5,300,000 tonnes of Zn. Mineral production is concentrated in geologic domains that approximately coincide with the boundaries of lithotectonic domains. We have compared the geology and mineral deposits of different domains to illustrate their distinct metallogenic signature. Certain domains are dominantly gold-producing (Cadillac-Malartic, Val-d'Or, Caopatina), others are base-metal producers (Matagami and Normetal), while others produce both gold and base metals ( Rouyn-Noranda, Chibougamau, Casa-Berardi-Joutel).Gold is extracted from quartz-rich vein deposits (for example, Val-d' Or), sulfide-rich veindeposits(Cadillac or Chibougamau) and from volcanogenic massive sulfide deposits ( Rouyn-Noranda). Base metals are generally mined from volcanogenic massive sulfide( RouynNoranda, Matagami, Normetal), although certain vein deposits yield base metals (Chibougamau) . Certain sectors are dominantly zincrich (Matagami, Normetal)."

Jan 1, 1990

By Alain Simard, Andre Gobeil, Sylvain Lacroix, Maurice Rive, Denis Racicot, Pierre Verpaelst

"The Abitibi volcano-plutonic belt forms the major portion of the Abitibi lithotectonic subprovince in the Superior Province. The Abitibi belt is composed essentially of"" (1) approximately 2.7 Ga old volcanic and sedimentary rocks; and (2) gabbro, tonalite, granodiorite and syenite intrusions occurring in well-defined prekinematic ( synvolcanic ), synkinematic and post-kinematic plutonic suites. Most of these rocks are metamorphosed to greenschist facies. Regional multi-phase deformation affects the volcano-sedimentary rocks. Deformation was initiated as these rocks were formed, and peaked at the end of the Keno ran orogeny with the emplacement of granitic batholiths.There are 145 former and current mines in the Quebec segment of the belt. To date, more than 420 Mt of ore have been extracted yielding 1,600 tonnesof Au, more than4,000 tonnesof Ag,4,400,000 tonnes of Cu and 5,300,000 tonnes of Zn. Mineral production is concentrated in geologic domains that approximately coincide with the boundaries of lithotectonic domains. We have compared the geology and mineral deposits of different domains to illustrate their distinct metallogenic signature. Certain domains are dominantly gold-producing (Cadillac-Malartic, Val-d'Or, Caopatina), others are base-metal producers (Matagami and Normetal), while others produce both gold and base metals ( Rouyn-Noranda, Chibougamau, Casa-Berardi-Joutel).Gold is extracted from quartz-rich vein deposits (for example, Val-d' Or), sulfide-rich veindeposits(Cadillac or Chibougamau) and from volcanogenic massive sulfide deposits ( Rouyn-Noranda). Base metals are generally mined from volcanogenic massive sulfide( RouynNoranda, Matagami, Normetal), although certain vein deposits yield base metals (Chibougamau) . Certain sectors are dominantly zincrich (Matagami, Normetal)."

Jan 1, 1989

By David R. Beadman

The Fleming method is widely used for the analysis and prediction of single pile behaviour under maintained loading. The method does not distinguish between bored and driven piles. Driven piling avoids the need to dispose of spoil from the pile installation and is therefore becoming increasingly attractive. This paper considers the theoretical effects of the possible preload at the base of a driven pile after installation, using the hyperbolic functions as defined by Fleming. The Fleming method is reviewed and the equations and analyses are adapted, using spreadsheets, to allow for a possible preload. The simplifying assumption of the effect of the elastic compression of the pile is also reviewed and a more analytical method adopted to assess the elastic compression. Some driven pile test data is analysed to consider the possible effects of the preload on the performance of a driven pile and to test the theoretical relationships that are developed in the paper.

Jan 1, 2006

This session was devoted to Surface Mining. Presiding was Virgil W. Carmichael, Vice President- Exploration, North American Coal Corporation, Bismarck, North Dakota, and John (Jack) F. Ratchye, Manager of Marketing and Resources, Peter Kiewit Sons' Co. Mining District, Sheridan, Wyoming. Subject-The new Federal Surface Mining Regulations-a thorough briefing as to content of law and how it will affect western mining. Introductory Speaker: William Hynan, Senior Vice President, National Coal Association, Washington, D.C. (See index for printed text of Mr. Hynan's paper.) Panel Members: The first speaker was George M. L. Robinson, Senior Hydrologist, Peabody Coal Company, Denver, Colorado. Mr. Robinson has a B.S. Degree from New Mexico University, Portales; Masters in Hydrology, Kent State, Ohio.

Jan 1, 1978

By J. Matos e Silva

The paper refers five examples of executed diaphragm walls with one to five levels of anchorages. For each example a comparison is made between the results of the design using the traditional criteria and the Eurocode 7 recommendations. A comparison is also made with the behaviour of the diaphragm walls during the construction phase. From the referred examples the author presents his conclusions.

Jan 1, 2002

By John W. Crutchfield, Emil F. Bowers

This paper presents the initial results of a pressure maintenance by water return project in the Lower Pawelek reservoir of the Falls City Field, Karnes County, Southwest Texas. Production is from the Lower Wilcox section at an average depth of 6,030 ft on the downthrown side of a "down to the coast" fault. Of particular interest is that the reservoir oil is high gravity and low viscosity but far undersaturated with gas at the original reservoir pressure and temperature. The early pressure and production history indicated only a partial or limited water drive, and this fact, coupled with the characteristics of the reservoir fluid and artificial lifting problem.. made advisable the water injection program to maintain reservoir pressure. The paper includes a description of the reservoir and reservoir fluids, the pressure and production history, a description of the water injection facilities, and the results of reservoir calculations involving Hurst's unsteady state flow and the material balance equations for calculation of water influx and prediction of the pressure-production relationship at various rates of withdrawal. The reservoir calculations and initial field results indicate that reservoir pressures in excess of 85 per cent of original pressure can be maintained by control of water injection even at very high rates of production. INTRODUCTION The purpose of this paper is to report the initial results of a pressure maintenance by water return program in the Lower Pawelek reservoir, Falls City Field, Karnes County. Texas, and to calculate an empirical relationship between pressure and production in this limited or partial water drive reservoir. Location The Falls City Field (Fig. 1) is located two miles north of the town of Falls City in Karnes County, Texas, and is approximately 50 miles south-southeast of San Antonio on U. S. Highway 181. Discovery and Development The initial block of leases was taken after a surface geological survey identified a major east-west fault and closure on the south or downthrown section. The discovery well, Southern Minerals Corporation's Joe F. Bartosch 1; was completed at 4,650 ft in the Lower Bartosch sand in December, 1944. Drilling was continuous until December, 1946, and resulted in the discovery of 12 oil reservoirs between 4,600 and 6,050 ft in the Middle and Lower Wilcox formations. These are shown on the cross-section (Fig. 2). As of the current date there are 64 oil wells completed as follows: Southern Gulfshore Magnolia Minerals Oil Petroleum Reservoir Corp. Co. Corp. Total Upper Bartosch 0 0 0 0 Lower Bartosch 16 0 0 16 Shulze 7 0 1 8 Upper Faires 2 0 0 2 Lower Faires 4 0 0 4 Upper Moczygemba 0 0 0 0 Lower Moczygemha 2 0 0 2 Olinick 2 0 0 2 Upper Martinez 0 0 0 0 Lower Martinez 5 0 0 5 Upper Pawelek 0 0 1 Lower Pawelek 27 1 3 31 Total 65 2 4 71

Jan 1, 1950

By William Kendall

"A tremendous amount of research, analysis, and engineering time is used to design a proper roof support system including the type, length, and location of the roof bolts. Unfortunately, since the roof bolts are being installed under unsupported roof, the exact location for the bolt holes cannot easily be determined and then marked onto the roof. The actual location where the roof bolts are installed is typically left to visual estimates by the operator. This frequently results in either (1) the operator overestimating the space between roof bolts and installing more bolts than required, thereby increasing cost and reducing efficiency; or (2) the operator underestimating the space between roof bolts and installing fewer bolts than required, thereby reducing safety, leading to potential roof failure or possible violations.A patented laser light grid system has been developed by J .H. Fletcher and Monitech, a South African Company, to aid in proper machine positioning in the heading and proper bolt spacing. The system can also show when an entry is over width, requiring additional roof support. The system is relatively simple and inexpensive. The concept is applicable across the full range of roof bolters from low to high seams and from single boom to multiple boom bolters. The system can be configured to meet most bolting patterns.The system consists of several very small 1 milliwatt, class 2, line type lasers that project a line onto the roof. The actual laser is 27mm in diameter x 47mm long (1"" x 1.8""). In South Africa it is approved as intrinsically safe and is mounted inside a 50mm diameter x 64mm long (2""x 2.5"") protective housing. In the USA, we are seeking an X/P approval and the laser will be mounted in a headlight enclosure 110mm diameter x 125mm long (4.3"" x 5""). Fifteen of the systems have been installed in South African coal mines with good results.The system has aided the mines in meeting the bolt spacing tolerance used in the Republic of South Africa, which is typically 15% of the nominal bolt spacing or 7 in for 4-ft bolt spacing. Fletcher has submitted the system to MSHA for approval in the US."

Jan 1, 2016

With the launch of Immersive Technologies' next generation of Advanced Equipment Simulators for the mining industry, correlating and influencing safety, productivity and maintenance with operator competency improvements is now made even more effective. In early 2008, Immersive assembled a project team to investigate the potential linkages between operator competency and performance. Advanced Equipment Simulator Users with a range of sophistication were interviewed and consulted. The result was new and enhanced 'value realisation' programs to directly assist mine sites to deliver the expected return on investment (ROI) from simulators and operator competency development. In just over one year, 29 mine sites around the world have benefited from 34 completed programs. Case studies have been compiled to demonstrate the impact of the implementation of this approach, including at the following operations: Anglo Coal - Callide (Australia), Freeport McMoRAN - Grasburg (Indonesia), Equinox Minerals - Lumwana (Zambia), Peabody Energy - Cabllo (USA), and Xstrata - Lomas Bayas (Chile). Significant performance improvements have been achieved including: reductions of 47 per cent in gear shifting and 37 per cent in over speed errors, improvements of 68 per cent in park break errors and 12 per cent in spotting time, and increase of 54 per cent in passing emergency fire handling competency tests. This presentation draws on these case studies to clearly demonstrate the linkage between improved operator competency through the implementation of training programs tailored around Advanced Equipment Simulators and production performace measured by a range of standard metrics at mines around the world.

May 1, 2010

By C Zhang, I Canbulat, G Fan, D Zhang, C Wang

A clear understanding of the intensity of coal and rock burst is the basis for future research on burst mechanism and control. There has been a wide variety in the description of coal and rock burst damage at different countries using multi-methods, which makes the common understanding even more challenging. Therefore, this paper presents a broad review on the quantifications of intensity of coal and rock burst and seismic risk around the world, considering critical factors including seismic energy, magnitude, peak particle velocity and ejection velocity. It is found that the seismic energy of coal and rock burst can widely range from 0.002 MJ to 60000 MJ, with equivalent Richter magnitude from -1 to 4. The daily seismic energies can be used for seismic risk potential assessment, with energy levels from 0.1 KJ to 10 MJ, which is much lower than the burst sources. The magnitude of the seismic events can be also estimated based on the weight of damaged coal mass and human senses of vibration and sound. For the seismic intensity represented by peak particle velocity (ppv), it keeps constant within fault radius and attenuates with a speed of 1/r4 and 1/r in near and far field respectively, thus it is possible for a small seismic event to induce considerable ppv causing severe damage if the epicentral distance is small enough. There has not been a strong correlation between the ejection velocity and ppv, as seismic energy is only one of the energy sources that contribute to the kinetic energy of burst damage. CITATION:Wang, C, Zhang, C, Canbulat, I, Zhang, D and Fan, G, 2018. Intensity quantification of coal and rock burst risk – a review, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 223–233 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By W. J. Fene, R. D. Currie

The value of protective clothing in the prevention of injuries has long been recognized in many of the leading industries , but the adoption of the idea into mine safety programs is comparatively new . Once started , however , the idea has grown rapidly and the results already obtained by mining companies have shown that it is fundamentally sound . Both coal and metal mining companies are rapidly adopting these protective measures , and since 1924 many mines have become well equipped with eye , head , and foot protection . At the present time approximately 70 percent of the employees in the anthracite mines of Pennsylvania are provided with safety hats . At many metal mines all employees are provided with safety hats, shoes , and goggles . The Pennsylvania mining law provides that all shaft · workers in anthracite mines shall wear protective hats . In According to a study³ made of the nature of 3,485 temporary injuries and of the parts of the body of underground coal mine employees most exposed to occupational hazards , the head and face were injured 665 times , the hands 856 times , and the feet 565 times . Of 2,555 temporary injuries in metal mines , the head and face received 484 , the hands 788 , and the feet 357 . a similar study4 made by a coal -mining company for the year 1928 , of 556 injuries the scalp received 9 , the skull. 4 , the eyes 47 , the hands 62 , the thumbs 21 , the fingers 141 , the ankle , the feet 51 , and the toes 35 . Probably most of these injuries could have been prevented by suitable protective clothing and equipment . This study also revealed that at least one injury occurred

Jun 1, 1933

By H. D. Van Veldhuizen

The Multilateral Investment Guarantee Agency(MIGA) is part of the World Bank Group, and has as its mission the facilitation of foreign direct investment by providing political risk insurance (guarantees) to foreign investors and lenders. As a development institution, MIGA is required to ensure that the projects that it insures will bring development benefits to the host country. Demonstration of this includes review and analysis of the environmental and social soundness of a prospective investment. Environmental guidelines and policies developed by the World Bank Group are important components both in analyzing the environmental and social soundness of a prospective investment and in risk management. MIGA has recently formalized and adopted environmental assessment and disclosure policies. The approach taken by MIGA to environmental review of investments and implementation of these policies is described in this paper.

Jan 1, 2000

By W. L. Fink, H. C. Stumpf, L. A. Willey

VERY few studies of the aluminum-sodium system have been reported. Heycock and Neville1 were unable to detect any solubility of sodium in liquid aluminum. Mathewson2 prepared an equilibrium diagram consisting of two horizontal lines at the melting points of the two metals. He was unable to detect solubility at either end of the system. Scheuer3 first developed a method for the chemical determination of sodium in aluminum and then studied the solubility of sodium in liquid aluminum. His method involved heating aluminum with excess sodium under hydrogen until the two liquids were at equilibrium, chilling the melt, and analyzing the aluminum-rich layer. He reported the solubility to be 0.l0 pct sodium at 700°C, 0.115 pct at 750°C, and 0.128 pct at 800°C. This paper on the aluminum-sodium system is the twenty-first in a series from the Aluminum Research Laboratories describing equilibrium relations in aluminum alloy systems. MATERIALS The alloys for this investigation were prepared from electrolytically refined aluminum (99.99 pct) and sodium of reagent quality conforming to specifications of the American Chemical Society.4 Chemical analysis of the aluminum showed the following impurities: 0.002 pct Si, 0.002 pct Fe, 0.002 pct Cu, <0.001 pct Mn, 0.002 pct Mg and 0.001 pct Na. The sodium content of all alloys was determined by either chemical or spectrographic standard procedures5 No. IIA and No. SII respectively. DETERMINATION OF LIQUIDUS The boundary of the miscibility gap was determined by a modification of the method of Scheuer3 and of that used by Henry and Cordiano.6 As finally developed the method was as follows: A fused alumina crucible 25 mm id with 75 mm depth and 1.5 mm wall thickness was placed on the bottom of a container made from a 4-in. length of 1 ½ -in. iron pipe and pipe caps. The space around the sides of the crucible was filled with 40 mesh crystalline alundum. A charge of 60 g of aluminum and 10 to 15 g of sodium was placed in the crucible, the sodium first being trimmed and rinsed with iso-pentane to remove kerosene. The container was tightly capped, filled with argon (99.6 pct pure), and heated to the desired temperature (between 670 and 800°C). A positive pressure of argon (about 8 mm of mercury) was maintained through a small pipe to the upper cap. After soaking for from 2 to 5 hr, the container was quenched by directing a stream of water onto the base, so that solidification of the aluminum-rich layer was rapid and essentially unidirectional. Analyses were made on drillings taken from the bottom of the ingots after machining off the surface layers. Pre-

Jan 1, 1948

By M. E. Taranenko, V. A. Krivonosov, S. A. Nemykin

"In concentrating production energy-consuming power installations are wide used, the most powerful of them are the wet autogenous grinding mill operating in closed circuit with a spiral classifier. The analysis of the current state of the automation of the grinding process shows that the reserves for maximizing productivity and minimizing electricity consumption have not yet been exhausted on the existing process equipment. Usage of the achievements of the modern management theory reveals an opportunity for further optimizing of the grinding process. The purpose of the research is to develop an automated control system of complex ""the mill-classifier"" to conduct the grinding process in the most operating efficiency, ensuring the maximization of productivity and minimization of specific electricity consumption. The main idea of this work is to study the specific features of the ore grinding process and creation on this basis of automated control system complex ""mill-classifier"" which allows to find and to maintain the optimal mode of grinding based on identification of the current object parameters, observance and regulating of the object state coordinates. Research methods. We used the methods of system analysis, mathematical statistics, modern automated control theory, theory of systems identification, optimal control, modelling of dynamic processes. Developed scientific provisions: - identification algorithm of the loading sub-system management object of complex ""mill - classifier"" allowing to obtain the unbiased estimators of its parameters according to the data of normal object exploitation; - observing device, which differs from the classic version of the observer Luenberger with possibility of estimating not only the state coordinates of the control object, but also the low-frequency perturbation component; - automated system stabilizing the active power of the grinding mode on the basis of a states controller with Luenberger observer; - structure of the software and hardware that implements the developed models, algorithms, methods of control, management and optimization in the framework of the automation of grinding."

Jan 1, 2018

By Stephen Royce

[PAGE Ground Movement Adjacent to a Caving Block in the Climax Molybdenum Mine (TP 2000 by JOHN W. VANDERWILT, Min. Tech., May 1946. Discussion by STEPHEN ROYCE and the Studies of the Design of Shaped Explosive Charges and Their Effect in Breaking Concrete Blocks (TP 2157 by GEORGE B. CLARK, Min. Tech. May 1947. Discussion by PHILIP B. BUCKY, V. H. CLARK, E. D. GARDNER, M. H. HAWKINS, H. L. WALKER, and the author) 2 See TP 2377, Min. Tech., May 1948 for discussion of San Manuel ProsPect (TP 2255 by H. J. STEELE and G. R. RUBLY, Min. Tech., Sept. 1947. Discussion by L. KENNETH WILSON, ELDRED D. WILSON and the authors)] Ground Movement Adjacent to a Caving Block in the Climax Molybdenum Mine STEPHEN ROYCE•-It is interesting to note from B, Fig 2, how closely the subsidence limits approximate to the 60° angle of draw, which is so commonly found to rule in large scale rock subsidence. The tension cracks shown at B are commonly found in the initial stages of subsidence movement and spread like a halo about subsidence limits as movement extends. These tension cracks usually grow into escarpments later on. Apparently from the illustrations and description given, a system of vertical fractures is the predominating weakness in the wall rock at Climax, and therefore both tension cracks and escarpments are prevailingly vertical in attitude. The illustrations in Mr. Vanderwilt&apos;s article seem to conform to the general rule that yield by subsidence is heralded by tension cracks which foreshadow the appearance of the subsidence scarps which are both described in the paper and shown in Fig 2. The difference between the B side and the A side of Fig 2 is apparently caused mainly by the vertical fracturing which controls subsidence at Climax as compared to the relatively homogeneous rock formation at A upon which the original figure in Peele&apos;s Handbook was based. The draw at B is exactly 60°, while the draw at A is a little flatter. The influence of the vertical fractures explains the difference. The surprising feature is the relatively small deviation from the general 60° draw line, which is about the average of rock subsidence experience. The influence of local fracture systems, faults and bedding in controlling subsidence all the way from extremely low angles of draw to vertical is rather fully discussed in the Peele&apos;s Handbook article referred to. The more illustrations of subsidence there are published the better will be our knowledge. The general principles are pretty well established. The wide local differences reflect the effect of local conditions. This paper is a very valuable contribution to the subject, and for the benefit of the mining industry, it is to be hoped that there will be many more such clear and concise presentations. Particularly block caving is apt to be of greatly increasing importance in the future of a mining industry that must meet high labor costs. More examples of block caving from small scale to large scale operations like those at Climax will serve a vital need. JOHN W. VANDERWILT (author&apos;s reply)-I would like to thank Mr. Royce for his discussion; however, in his comments the meaning of subsidence, draw and tension cracks is not entirely clear. As used in my discussion of subsidence at Climax, subsidence refers to movements involving appreciable downward displacement. Tension cracks indicate only

Jan 1, 1947

By Trevor R. Ellis

The extractive industries addition to the International Valuation Standards (IVS) is scheduled for publication in the next edition of the IVS book in January 2005. This will provide guidance for valuation of minerals and petroleum industry assets of all types for all appraisal uses. It will provide asset valuation support to the International Financial Reporting Standards for the stock markets of the world, and a global umbrella standard which can be supplemented for local needs by institutes and regulators. This paper discusses implementation of the IVS within the minerals industry and important issues that the industry should confront.

Jan 1, 2005

By L. Shevenell, L. Stillings

The Acid Drainage Technology Initiative-Metal Mining Sector (ADTI-MMS) has established a Pit Lake Committee to enhance the science and understanding for the long-term management of pit lakes. Participation in this new committee is from members of federal and state agencies, industry, and academia, including numerous individuals representing 10 states. Work has begun on a pit lake literature search and review, database, classification, and sampling and monitoring procedures document. Coordination with the International Network for Acid Prevention (INAP) has been established. Future work will include preparing a prediction and assumption verification document, a report identifying variables upon which water quality is dependent, and an applied remediation technologies document, including an evaluation of the effects of backfilling.

Jan 1, 2002

By D. A. Thomas, E. S. Meieran

Tungsten wires were examined by transmission electron microscopy after drawing and after high-temperature annealing. Drawn wire consists of highly elongated grains called fibers, whose long axis is parallel to [110]. Each fiber is ribbon-shaped, with the wide dimension of the ribbon parallel to (001) and the narrow dimension parallel to (110). Furthermore, most fibers are bent about [I10] and twisted along their length. The fibers are divided into cells, which in some cases contain a platelet substructure lying on (110) planes. The misorien-tations of these platelets accumulate to allow the macroscopic twist of the fibers. During annealing, several competing reactions occur, starting at different temperatures and progressing at different rates. Among these processes are fiber-boz~ndary migration, polygonization, dislocation rearrangement, and possibly impurity segregation. The fiber-boundary migration accompanied by the formation of transverse boundaries during polygonization leads to an equiaxed grain structure although recrystal-lization does not occur. There is a relationship between the flow stress of the wires and their average subgrain width in the form sy = s0 + kyd-1/2 . Also, there appears to be a relatio&apos;nship between wire ductility and the formation of transverse boundaries during annealing at about 800°C. THERE have been many investigations of the structures and properties of tungsten wires1-4 due to their commercial importance for use as lamp filaments. The structural studies have so far been limited to optical microscope and replica electron-microscope studies. due to the difficulty of .-me- paring from wires thin foils which can be examined by transmission electron microscopy. However, this difficulty has been recently overcome,5 and it is now possible to examine tungsten wires by transmission electron microscopy as well as by other techniques. In this paper, the structure of drawn tungsten wire is described, as are the changes in the structure during high-temperature annealing. Some discussion of the relationship between structures and properties is also given. EXPERIMENTAL MATERIALS AND PROCEDURES Commercial 0.030-in.-diam doped tungsten wires drawn at progressively decreasing temperatures between about 1400° and about 800°C were examined. The composition, mechanical properties, and optical microstructures are described in detail elsewhere.&apos; All experimental materials were vacuum-annealed for 10 ot 30 min at temperatures at 100°C intervals between 700° and 2000°C. Specimens were thinned for examination in the Siemens Elmiskop I electron microscope by the method of Meieran and Thomas.5 STRUCTURE OF AS-DRAWN WIRE The optical microstructure of as-drawn tungsten wire has been described by Peck and Thomas.7 They observed that wire in longitudinal section consists of highly elongated grains called fibers whose width varies between 1 and 10 µ, while in transverse section the fibers appear to be elliptical in cross section and bent about their common [110] wire axis. They explained this unusual appearance as being due to the drawing of a bcc material with a [110] texture, and predicted that the wide and narrow planes of the fiber cross section would be parallel to (001) and (110), respectively. The fibers apparently bend about the [110] axis during drawing to maintain grain boundary continuity during drawing. Transmission electron microscopy offers a way of checking these predictions as well as providing a more detailed picture of the wire structure. Figs. 1, 2, and 3 are typical electron micrographs of

Jan 1, 1965

By M. Z. Rashad

The intersection of joint sets and excavation planes leads to removable blocks which can be expected to fall or slide. The amount and cost of supports required to stabilize these blocks of excavation are related to the number and dimensions of key blocks, the mechanical properties of joints and the active forces present. In this work, the application of the block theory in the study of the kinematics and stability of removable blocks is investigated considering any number of sliding faces for some Egyptian limestone quarries.

Jan 1, 1993