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By Y. V. Vasylchuk

This paper presents an algorithm for optimizing the classification of surface mine material subject to excavating constraints. High-resolution expected profit models are input and optimized to classification maps subject to site-specific rectangular excavating constraints. This optimization problem defies traditional closed-form analytical solutions; a practical heuristic algorithm has been developed to quickly determine the optimal final destination for the material subject to realistic constraints. The optimization is fast and generates results that achieve up to 98–99% of the total expected profit achieved with free selection. This algorithm provides a fast viable option for practical application in short-term grade control and in managing multiple realizations in long-term resource estimation.

By J. P. Schde

The authors deal with nickel production and usage patterns, nickel's first-use and end-use, examples of nickel applications in modern technology, e.g., energy generation and conservation, environmental protection, the oil and gas industry, construction and machinery, food production, conservation and distribution, consumer durables and the like. A special section of the paper is devoted to new applications of nickel in the electronic industry, modern corrosion control and the building and construction industries. The need to defend traditional markets for nickel while striving to find new applications, is also stressed.

Jan 1, 1988

By K. L. Paciorek

Organic materials utilized as cable Jacketing, cable insulation, standoffs, insulating boards and potting compositions were identified and d literature survey performed to obtain the required thermal oxidative and moist tracking data. Thirty representative compositions were procured and subjected to thermal and moist tracking evaluations. Tracking was found to invariably result in ignition or glow of the test specimen. Influence of parameters such as electrolyte strength and composition, temperature, conductor spacing, and electrode material were investigated. Volatile s produced by selected insulators on thermal oxidative and electrical stress were identified, quantitated, and their potential impairment action upon a current interrupter assessed.

Jan 1, 1980

By H. P. LeVan

The aced for reliable reserves of the essential element, manganese, has been a continuing concern of the Federal Government for more than three decades. Because of the increasing vulnerability of outside sources of supply efforts have been intensified to find a means for beneficiating United States domestic deposits. The deposits of most interest would of necessity be near, or have access to, suitable transportation to processing plants. The Georgia manganiferous iron deposits represent some 10 million tons4 of ore readily available to southern iron and steel industries, if a manganese recovery process capable of functioning in the presence of large quantities of iron can be developed. In addition, a successful method for beneficiating the Georgia ore could produce a significant quantity of high-grade iron concentrate. The Differential sulfatization process developed 47 the Bureau of Mines5 seemed to be well suited for this application, particularly because it results in low concentrations of iron in the leach liquors with relatively complete extractions of manganese. In this process, manganese in the presence of iron is preferentially reacted with sulfur dioxide at elevated temperatures and subsequently extracted with water.

Jan 1, 1962

The prevention of silicosis by metallic aluminium has been reported by Denny, Robson, and Irwin in two papers. The first was published in 1937; the second in 1939. The results definitely established that silicosis was prevented in animals by the inhalation of small quantities of aluminium. The present communication records subsequent progress in this field of research.HARMLESSNESS OF ALUMINIUMAnimal experiments having served their purpose, it became necessary to consider means to test the discovery on humans. A question for immediate consideration was: Is aluminium harmful to man when inhaled as a fine powder? While the animal experiments were reassuring, since they conclusively showed the powder to be innocuous when breathed by animals, it was, nevertheless, desirable to have additional reassurance with regard to its effect upon human beings.Through the courtesy of the Aluminium Company of America and especially the valued interest in this problem displayed by that Company's Director of Research, Dr. Francis C. Frary, a study was made of the records pertaining to the health of a group of 125 employees who had for many years been engaged in the manufacture of finely powdered, metallic aluminium for the paint and ink industries. The conditions were such that these employees had inhaled varying and oft-times very dense concentrations of this powder daily over periods ranging from 6 to 23 years, the average 101 the group being 12 years. X-ray pictures of their chests showed no abnormalities attributable to aluminium. Their general health seemed better than that of the 3,000 workers in other sections of the plant. In fact, the early films of three employees in this group of 125 showed shadows suggestive of minimal tuberculosis, which shadows were not discernible in films taken after considerable periods of exposure to aluminium powder.The harmlessness of aluminium was; by this study, reasonably well established at the outset, a finding subsequently verified by Ontario research on humans.PROPOSAL TO TREAT HUMAN SILICOSISBased upon these findings, a proposal to treat silicotics with aluminium was discussed by officials of the Mclntyre Mine and the Banting Institute.

Jan 1, 1945

The STATE MINERAL SUMMARIES publication provides estimated data and summaries of mineral activities at the State level for 1993. Most of the estimates are based on nine months data. Individual State summaries are published separately as State Mineral Industry Surveys and copies can be obtained from the appropriate State mineral officer. In an effort to facilitate the rapid dissemination of information and publications produced by the U.S. Bureau of Mine, an electronic document dissemination system is now available for use. MINES FaxBack is a simple-to-operate automated fax response system that operates 24 hours a day, seven days a week. All a user needs is access to a fax machine with a touch-tone telephone. MINES FaxBack can be accessed by calling (412) 892-4088, using the touch-tone telephone attached to the user's fax machine. After calling MINES FaxBack, the requester is guided by a series of voice messages to assist in ordering the desired documents.

Jan 1, 1994

By Cuppam Dasarathy

The incidence of liquid inzmiscibility in binar)) indium alloys has been theoretically analyzed on the basis of the Hildebrand-Alott equation. Bedictions of miscibility or otherwise Imve in general been found to agree with those phase diagrams that are already publislzed in the literature. Out of a total of 27 systems, where either the complete phase diagrams are published or liquid immiscible behavior is reported, the Predictions agree with the experimental data in 25 systems, the exceptions being the Te-In and Ni-In systems. According to the equation, liquid immiscibility is also indicated in the binary alloys of indium with K, Rb, Cs, Na, Sr, Ba, Ti, Zr, V. Nb(Cb), Ta, W, U, Re, Ru, Rh, Os, and Ir. RECENT investigations by the author have shown that indium when alloyed with iron, chromium, and cobalt shows liquid immiscible behavior.1"3 The Fe-In phase diagram shows a wide range of compositions where the liquids are immiscible.4,5 No intermediate phases are present in this system. No precise information is available about the extent of liquid immiscibility in the Co-In system. However, it is certain that there is a range of compositions where the liquids are immiscible and that there are two or three intermediate phases,376 in the system. Liquid immiscibility is also strongly indicated in the Cr-In system and no evidence was obtained in the brief investigation to indicate the presence of intermediate Cr-In phases.2 The present paper deals with a theoretical analysis of binary alloys of indium with certain elements of the periodic table and indicates the systems where liquid immiscibility may be expected. The incidence of liquid immiscibility in binary systems has been theoretically examined by many workers and many excellent papers are available on the subject. In this paper, the alloy systems are examined on the basis of the more recent ideas proposed by Mott.7,8 It has been claimed8 that the Mott parameter predicts the incidence of miscibility or otherwise with reasonable accuracy and consistency. BACKGROUND TO MOTT&apos;S APPROACH Hildebrand applied his immiscibility rule for non-polar liquids to various alloy systems.9 The basis of this rule is that the equation for the excess free energy of formation of a liquid solution is rather similar to the theoretical expression for the energy of mixing of a regular solution. He postulated that when the heat of mixing is sufficiently high, separation into liquid phases will occur and the condition for complete CUPPAM DASARATHY is at the Research Centre, British Steel Corporation, (South Wales Group), Port Talbot, Glamorgan, Great Britain. Manuscript submitted March 12, 1969. IMD miscibility was shown as where VA and VB were the atomic volumes of the components A and B, and ?EV the energy of vaporization of the component. The term (?EVA/VA)1/2 was regarded as a measure of the binding energy of the component A and was called the L&apos;solubility parameter" 8A. On this basis immiscibility occurs when 1/2(VA+VB)(bA-bBf > 2RT [2] Apparently, however, there were several inconsistencies in that according to Eq. [2] several systems known to be miscible in the liquid state were predicted as immiscible. MOTT&apos;S ANALYSIS ~ott&apos;" regards that the reason for the inconsistencies arising out of Hildebrand&apos;s equation was largely due to the electrochemical attraction between the two elements, not being considered. Hence, Eqs. [I] and [2] were modified by taking into account the electro-negativities of the two elements XA and XB, and Mott arrived at an equation for immiscibility, i(VA + VB)(6A - aB)2 - 23,Q60n(XA - XBf > 2RT [3j which can be written as i **&£*&* >&apos;*°™- &apos;• HI T being the melting point of the more refractory component of the system. In Eq. [4], the numerator was called the Hildebrand term, the denominator, the electronegativity term, and their ratio, the Mott number. Mott observed that if the Mott number of a given binary system was greater than the maximum number of Pauling bonds which the two metals could form, then liquid immiscibility could be expected. The maximum number of bonds formed by a given metal was considered to be directly related to the number of bonding electrons available, i.e., to its maximum valency. Since the valencies of the elements considered vary from 1 to 6, Mott assumed that if the ratio of the Hildebrand term to the electronegativity term was >6, then immiscibility could be expected. On the contrary, if the ratio is <1, the metals should be miscible. Further, the alloying behavior is not only influenced by the valencies of the two elements but also by the relative atomic sizes that influence the types of packing and hence the coordination number. Mott considers that on average the maximum number of near neighbors of unlike atoms is 6. Thus, on both valency and size factor considerations, Mott concludes that the maximum number of bonds&apos; possible in any system was 6, this being the upper limit of the Mott number for miscibility. In considering the alloying behavior of systems with Mott numbers between 1 and 6, Mott plotted the num-

Jan 1, 1970

By F. V. Lenel

This discussion is concerned with the method of manufacturing, the design possibilities, and the properties of pole pieces for direct-current electric . motors and generators made from iron powder. In such applications as pole pieces, the electric and magnetic properties of the material are of major importance, therefore they are discussed somewhat more fully. However, the main advantage in making pole pieces from powders lies in the rapid and inexpensive method of manufacturing these pieces, and in the flexibility of design, rather than in their superior electrical properties. As a matter of fact, pole pieces from iron powder have found their principal field of usefulness in small electric motors for controls and similar applications where the highest possible flux density in a given design is not required. Fig. I shows a number of different designs for pole pieces made from iron powder. The steps involved in fabricating them are: (I) briquetting—with each stroke of the briquetting press a complete . pole piece is produced; (2) sintering, and (3) sizing, which is a one-step coining operation in a hand-operated punch press. Conventionally small pole pieces are made from laminated electrical sheet steel stock by punching out the laminations and riveting them together (Fig. 2). The powder method has the advantage of being rapid and inexpensive; also, it makes possible the molding of pole pieces with a round hub, which are better from a design standpoint, as will be shown later. It is difficult to make such round-hubbed pieces from laminated stock. The pole pieces could, of course, be machined from solid stock, but this method is not widely used. The raw material for making pole pieces from powder is straight iron powder without the addition of any alloying ingredients. However, the grade of powder used is of considerable importance, as will be shown later when the influence of the grade of iron powder upon the magnetic properties is discussed. Pole pieces are briquetted in the same way that other iron-powder machine parts are made. Because the pole pieces are flanged—i.e., they have a hub and a wing section—they are made in presses that apply pressure from both ends. For best mechanical and magnetic properties, the density throughout the piece should be even and also should be constant from piece to piece. For that reason a powder of constant compressibility from batch to batch is needed for briquetting pole pieces. One method of obtaining the required magnetic properties is to sinter the pole pieces at temperatures higher than are used for most iron-powder parts. A temperature of 2400°F. and an atmosphere of hydrogen has been found satisfactory. No automatic furnaces of the roller hearth or mesh-belt type have yet been developed for such high temperatures. A box-type furnace heated with Globar heating ele-

Jan 1, 1945

By Shirley F. Colby

The past 40 years have seen the sand and gravel industry grow from small roadside pits and holes in farmers&apos; back yards to giant corporations selling millions of tons of sand and gravel each year and owning plants representing huge capital investments in land and equipment. The days hen a man could "work out" his taxes by providing the materials for nearby roads are gone forever. In addition to the hundreds of privately owned and operated plants, Government agencies operate sand and gravel pits and plants to supply aggregates for the tremendous road-building and public-works programs in progress during the past few years. EXPANDING PRODUCTION In 1940 the send and gravel industry produced almost a quarter of a billion short tons valued at more than 110 million dollars. This compares with less than 2 million short tons worth 1 1/2 million dollars produced in 1902. The practice of screening sand and throwing away the gravel in the early days of the industry&apos;s growth has stopped, and in 1940 gravel constituted two-thirds of the total production. In 1906, the first year in which sand and gravel were reported separately gravel accounted for only one-

Jan 1, 1942

By A. N. Veltmeyer

"INTRODUCTIONTeck-Corona Operating Corporation's David Bell Mine is located 35 Km east of Marathon, Ontario. In conjunction with its 1000 tonne per day gold concentrator, the company operates an effluent treatment plant for the treatment of mill, mine and site effluents prior to environmental discharge. This paper provides a brief overview of treatment strategies and methods, employed to detoxify final effluent.WATER MANAGEMENTThe tailings impoundment basin, located 3 Km south of the plant site, provides storage capacity for all process effluents and site run-off. Basin supernatant (reclaim water) is recirculated to the plant for reuse as process water, in order to minimize fresh water consumption. As site run-off and limited fresh water intake exceed natural losses due to evaporation, reclaim water in excess of process requirements is passed through the effluent treatment (ET) facility to control tailings basin level by providing regulated discharge of environmentally acceptable effluent. (Figure 1)PASSIVE TREATMENTTo reduce treatment costs and burden on the ET facility, reclaim water is fed to the plant to take maximum advantage of natural destruction processes occurring in the tailings basin.These include: volatilizationphotodecompositionbiological oxidation and precipitationstorm water dilutionConcentrator recovery techniques (Figure 2) are directed toward maximizing gold recovery while limiting the addition and extraction of contaminants requiring disposal and eventual treatment.Currently ore ground to 90% -200 mesh is pre-aerated at pH 9.0 with lime for 18 hours prior to 30 hours cyanidation at pH 9.5 with low cyanide ion excess (70 ppm).Pre-aeration passivates cyanicides prior to cyanide contact. This reduces cyanide consumption and the formation of cyanide complexes. In conjunction with recovery requirements low pH is maintained to retard the dissolution of stibnite into its antimony and sulfide components."

Jan 1, 1989

Amongst representative men directing alluvial mining of erations in Victoria, some difference of opinion exists as to the best system of working the deep leads. The developmental operations of shaft-sinding, extending a reef drive, partially watering and rising up into the wash dirt are practically the same on all fields but subsequent mining is continued either on the Chiltern and Rulberglen or Ballarat systems, the latter being referred to by the Chiltern and Rutherglen miners as the &quot;down country&quot; system. In the former, the leading wash and cross drives are lept from 300 to 500 feet ahead of the reef drive, and in the latter the reverse method keeping the reef drive well ahead of all wash workingsis adopted.In the majority of alluvial mines in the southern and western fields, the initial work of defining the course of the lead is costly, owing to the thick superincumbent layers of hard basalt, to bore which costs from 9/- to 15/&#183; per foot. Unfortunately large sums of money have been wasted in this work, owing to a want of care and knowledge in the selection of bore sites, and improper recording of the strata pierced, thus handicapping alluvial mining and bringing boring operations...

Jan 1, 1902

By John K. Gustafson

The title of my talk is "The Gold Miner and the Future of Gold." This title might just as accurately have been stated as "Gold and the Future of the Gold Miner." Since prehistoric times gold has been sought by mankind for its beauty and its unusual physical and chemical properties. Early in the dawn of civilization it became the ultimate unit of value and lubricated trade between peoples. For at least 6000 years, gold has been used to barter for other commodities. It has been prospected for, treasured, made into works of art and personal adornment, and from time to time has been the object of conquest. Because of its predominant role in recent centuries as a basis for money, economists began to think of it solely in these terms. Annoyed by the disciplinary pressure of gold on the money manager&apos;s desire to manipulate money, the famous economist, John Maynard Keynes, characterized it as a "barbaric relic of the past", a characterization repeated by William McChesney Martin, Jr., when he was head of the Federal Reserve Bank. Gold, however, has physical and chemical properties that make it one of the most useful metals in the modern world.&apos; It is the most ductile metal known. An ounce of gold, for example, can be drawn into a continuous wire over 35 miles long. It also is so malleable that an ounce of gold can be beaten into films ten one-millionths of an inch thick sufficient to cover 68 sq ft of surface. It has a density of 19.3 and is so heavy that 1 cu ft of gold weighs more than half a ton. Gold is nonmagnetic and has a high electric conductivity, only slightly less than silver and copper. Gold is so inert to all the chemicals found in nature that gold coins and jewelry buried beneath the soil or at the bottom of the sea for thousands of years appear to be as bright and perfect as when they were first immersed. Finally, gold has an extremely high reflectivity both to light and infrared rays. Because of these qualities, in addition to its rare beauty, industrial and artistic uses of gold have been growing rapidly. On a world basis, a recent study estimated that in 1960 about 750 tons of gold were used for fabrication, and that the amount had grown to about 1296 tons in 1968. My objective in this talk is to discuss with you the present and future supply of and demand for gold on a worldwide basis and the effect these forces are likely to have on the price the miner can expect to receive for the gold he produces. This is a highly controversial and risky subject to discuss before any audience. Nevertheless, it is a subject that I live with constantly as Chairman of the

Jan 1, 1972

A methodology has been developed and demonstrated to be effective in reclaiming surface-mined land for a forestry post-mining land use. The Forestry Reclamation Approach (FRA) has been applied, almost exclusively, to flat or gently rolling surfaces. One of the primary steps in the FRA is to loosely grade the top 1.22-m (4-ft) of soil or substitute root growth medium to avoid excessive compaction. Concern has been expressed by regulators and the public that loose grading on steep slopes could lead to slope failures, which is one of the issues that SMCRA sought to correct. A field investigation was conducted at a steep-slope contour operation in eastern Kentucky to test the applicability of FRA in this setting. Final grading was performed according to FRA standards. The surface consisted of two distinct substitute rooting media. One was unweathered gray sandstone and the other was a combination of gray sandstone, brown sandstone, and topsoil. A variety of native hardwoods was planted following the FRA guidelines. The slope was instrumented with 70 survey monuments to monitor for mass movement. The reclaimed spoil was also characterized using bulk density and penetrometer resistance methods. The characteristics of both spoils are similar to those observed on flat to rolling surfaces where the FRA has been used and, after one year, approximately 70% of the trees had survived. There has been no major mass movement of the slope and slope stability analyses indicate that the application of the FRA has little impact on the overall stability of the slope.

Jan 1, 2011

By Frank Callanan

The Ameristar Casino expansion project included the design and construction of a 25-story hotel and 9-story parking structure expansion. The site is located in a floodplain on the banks of the Missouri River in Saint Charles, Missouri, where the underlying soils are potentially liquefiable. The geotechnical engineer performed subsurface exploration and analysis, which included site-specific seismic response and liquefaction, and provided geotechnical design recommendations. In the event of an earthquake, post-liquefaction settlement was calculated to be approximately 14 inches. Additional project constraints included wetlands protection, construction adjacent to the existing facility, flood protection and river bank stability. Because of the liquefaction issue, the geotechnical engineer consulted with a specialty geotechnical contractor on ground improvement methods. This consultation led to a proposal to eliminate deep foundations from the design and support the structures on shallow and mat foundations. The geotechnical engineer assisted the design team with foundation design analysis and value engineering assessments. Together with the project team, the geotechnical engineer used the data to evaluate foundation options and construction methods to overcome the site challenges and concluded that ground improvement was the optimum course of action. Because of the nature of the site constraints, a number of ground improvement methods were needed. The geotechnical engineer evaluated the methods proposed by the geotechnical contractor and provided the technical specifications for the ground improvement bid package, which included vibro-compaction, compaction grouting and micropiles. The ground improvement allowed for the use of shallow foundations (mat and spread footings), which provided the client with significant time and cost savings over the deep foundation alternatives.

Jan 1, 2009

By B. P. Watson

The Bushveld platinum group metal deposits are two distinct, shallow-dipping stratiform tabular orebodies which strike for many hundreds of kilometres. Mining is extensive, with depths ranging from close-to-surface to 2 300 m. The mining method is a variation of planar open stoping. Pillars are widely employed to support the open stopes. In the deeper levels, in-stope pillars are required to fail in a stable manner soon after being cut, and the residual pillar strength is used to stabilize the hanging wall. These pillars are commonly known as crush pillars. Little work has been done in the past to determine pillar peak and residual strengths, and pillars have been designed using experience and formulae developed for other hard-rock mines. This has led to over and undersize pillars with consequential loss of ore, pillar bursts and potential collapses. This paper describes a crush pillar design methodology, and provides design charts. Three mining environments were incorporated in the investigations, which included underground and laboratory measurements, analytical solutions, numerical model sand back analyses. The results of the study are suitable for the areas where the research was carried out, and may also be applied with caution in other similar environments.

Jan 1, 2010

By Barbara H. Scott Smith

"During the last two decades lamproites have joined kimberlites as the only two known primary sources of economic quantities of diamonds. This paper contrasts the petrography, primary and xenocrystic mineralogy and pipe geology of these petrogenetically separate rock types. The petrographic discrimination of kimberlites and lamproites from each other, as well as other rock types found during diamond prospecting, is discussed. Kimberlites and lamproites can be classified texturally and mineralogically. Such classifications highlight the differences between, and among, lamproites and kimberlites. The implications of these differences for diamond exploration programs are discussed, with particular emphasis on the application of petrography. IntroductionKimberlite was the term coined in the late 19th century to describe the host rock of diamond at the type locality, Kimberley, South Africa (Lewis, 1887, 1888). Innumerable kimberlites are now known worldwide; some of them contain economic quantities of diamond (e.g. South Africa, Botswana and Russia) while many are barren. Jennings (1989) suggests that less than 3% of the known kimberlites can be considered to be commercial. Kimberlite was thought to be the only important primary source of diamond for approximately a century. Until the late 1970s, lamproites were thought to be only academic curiosities. Some workers (e.g. Wade and Prider, 1940), however, did comment on certain similarities between lamproites and kimberlites and, hence, inferred a potential for lamproites to carry diamonds.The term lamproite was introduced by Niggli (1923) for leucite-bearing rocks from southeast Spain and Wyoming which had some unusual geochemical characteristics. Wade and Prider (1940) used the term lamproite (as defined by Troger, 1935) to embrace rock types found in the West Kimberley area of Western Australia. All the lamproites described by Wade and Prider (1940) form distinct topographic features. Subsequently in the late 1970s, additional pipes, which have little or no relief, were discovered in the same area, but only as the result of a major diamond exploration program (Atkinson et al., 1984; Jaques et al., 1984, 1986). Some of these bodies are diamondiferous. In 1979, the Argyle pipe was discovered in the East Kimberley area which, in terms of grade, is the richest known primary diamond deposit in the world with some parts of the body having grades greater than 500 carats/100 tonnes (Madigan, 1983; Boxer et al., 1989). All the initial new discoveries in Western Australia resulted from classic stream sampling for ""kimberlite indicator minerals"" (Atkinson, 1989)."

Jan 1, 1992

By K. K. Kelley

The collection and correlation of thermodynamic data concerning substances of metallurgical interest have constituted one of the major activities of the Pacific Experiment Station of the Bureau of Mines, at Berkeley, Calif., for the past several years. Earlier bulletins (32, 33, 34, 36, 36, 37, 38) s in this series are entitled: (1) Contributions to the Data on Theoretical Metallurgy. I. The Entropies of Inorganic Substances; (2) Contributions to the Data on Theoretical Metallurgy. II. High-Temperature Specific-Heat Equations for Inorganic Substances; (3) Contributions to the Data on Theoretical Metallurgy. III. The Free Energies of Vaporization and Vapor Pressures of In¬ organic Substances; (4) Contributions to the Data on Theoretical Metallurgy. IV. Metal Carbonates--Correlations and Applications of Thermodynamic Properties; (5) Contributions to the Data on Theoretical Metallurgy. V. Heats of Fusion of Inorganic Substances; (6) Contributions to the Data on Theoretical Metallurgy. VI. A Revision of the Entropies of Inorganic Substances-1935; and (7) Contributions to the Data on Theoretical Metallurgy. VII. The Thermodynamic Properties of Sulphur and its Inorganic Compounds. The present paper collects and discusses thermodynamic data relating to metal carbides and nitrides, with the view of obtaining usable heat and free energy of formation relationships. Pertinent data on both classes of substances are difficult to obtain experimentally and consequently are extremely rare; it is therefore necessary in many cases, if equations are to be derived, to introduce certain approximations and assumptions. Lack of adequate means of checking results by utilizing data of different types, such as was done frequently in the bulletins dealing with carbonates and sulphates, are readily apparent to anyone who has made even a cursory examination of the available information. Consequently, some of the relationships derived undoubtedly will be found to be inaccurate when more or better data become available. Nevertheless, in view of the importance of some of these substances, it appears worth while to consider the information available at present and to attempt the formulation of as complete a

Jan 1, 1937

By Floyd Varley

In deep and highly-stressed coal mining, advanced design practices are used to minimize the potential for damaging events to occur. Despite these design efforts, the hazard of coal mine bumps can not be completely eliminated. This paper will review current and historic work practices used internationally to minimize the hazard to miners from mining in conditions which could produce a bump. These site specific work practices have a common base in monitoring for conditions which could result in a bump and application of controls to prevent the occurrence or minimize the severity of an event where miners are working. Monitoring practices range from purely observational to semi quantitative. Control methods attempt to initiate events in a controlled manner, absorb the energy of a potential event or reduce the potential for or magnitude of an event by altering the stress conditions of the mine workings. Building from the experiences of other coal fields, an empirical framework to manage the potential hazard of coal mine bumps can be developed to enhance the level of safety provided by prudent mine design.

Jan 1, 2008

By James E. Parkes

The Silver Spring Transit Center is a new three-level transit center that will include bus loops for County, Metro and intercity buses, parking, and retail space. It replaces an existing bus station and connects to a busy metro rail station in downtown Silver Spring, Maryland. Significant site constraints in both plan and profile had to be dealt with in developing a design for support of the structure. Over 90 rock-socketed drilled shafts ranging in size from 3 to 7 foot in diameter were ultimately used to accommodate the limited space and large column loads, and to adapt to the variable rock surface at the site. Site access during design was limited due to the existing active bus station, so contract documents were adapted to include further explorations. Differences in anticipated and actual field conditions regarding the depth, quality, and variability of the rock had to be overcome in construction. Osterberg Load Cell testing during construction allowed for verification and optimization of the shaft design. Additional issues dealt with on this constrained site in an urban setting included construction staging issues, such as working around specialty contractors for tieback walls, blasting operations for rock excavation, productions issues for hard bedrock, as well as coordination issues with third parties, most notably the Washington Metro Area Transit Authority. Aspects of the foundation design and optimization, preparation of the contract documents to deal with the complicated nature of the project, and lessons learned from construction are also discussed.

Jan 1, 2011

By Hugh R. Rhys

The question of the desirability of recovering cullet from MSW in order to recycle it into the manufacturing of glass containers remains a controversial one. The main factors appear to be: 1. The position of the Glass Container Manufacturers Institute (GCMI), as the trade association for most container manufacturers, is that post-consumer cullet is a vital source of raw material. Present requirements are for: a) Flint cullet b) Non-flint cullet of known mix proportions c) Mixed unsorted cullet of known mix propertions c) Mixed or non-flint cullet of unknown mix proportions. A market balance for these products exists, and this might somewhat limit the outlets for (b), (c) and (d), or severely limit the outlet for (d) alone. 2. The color specifications are rather strict. With cullet admixtures of 20% of the melt or more, and the use of decolorisers in a flint furnace discouraged because their action is reducing in a process which requires an oxidising environment, color contamination in a flint furnace is serious.. For amber and green furnaces (reducing) it is less serious, but in order that the quantity of decolorisers may be controlled, the color balance (as a measure of the Fe and Cr content) of the admixtured cullet should be known. 3. Why not simply color analyze, either by a continuous on-stream or off-stream: photo-electronic analysis, or by systematic batch sampling (with some kind off electronic surveillance of the mainstream) and just send mixed, color measured cullet to only amber and green furnaces? The flint would-be simply included in the mix. This is probably technically feasible, but is subject to the market limitations noted in point1.

Jan 1, 1975