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By Raymond J. Poletto

This paper describes the special problems that occur with the construction of diaphragm walls and discusses the lessons learned during the repairs of structural walls. Although diaphragm or slurry wall technology and equipment has vastly improved since its development in the late 1950?s, significant problems still occur. Key issues are repairs related to panel joints between wall panels, concrete defects associated with tremie concrete problems, leaks and other defects at tieback reservations or inserts, wall leaks within the plane of the wall and surface repairs. The paper supports the position that diaphragm walls are relatively watertight when properly constructed, but cautions that it is necessary to address potential problems in the design stage and allow for flexibility in construction so that the problems that occur can be corrected once encountered. Due to the fast track nature of most projects the time available for design, detailing and construction is limited. As a result, insufficient attention to detail by any of the responsible parties can lead to imperfections and defects in the wall. The authors describe the nature of these problems and their potential resolution based on ?lessons learned.? The timely response to wall problems is essential to the successful completion of a diaphragm wall project. Appropriate repairs have resulted in largely successful jobs starting with the World Trade Center in New York City. The authors? total 80 years of experience as the engineer of record and designer, inspector and contractor?s representative for the diaphragm wall results in a unique insight to deal with these problems.

Jan 1, 2011

By Nathaniel Arbiter

The increasing size of flotation cells as the use of flotation has increased is traced from the first United States application of the process in Montana in 1911 through the following eight decades, using data from the Taggart handbooks (1927) and (1945), from the SME Handbook (1984), and from recent manufacturers' catalogues and other sources for the 1980s and 1990s. With the earliest mechanical cells less than 1 m3 (359) in volume and the largest now available at 200 m3 (7,000ft3), three requirements are necessary: 1) demonstration of advantages in replacing smaller volume by larger volume cells; 2) estimating power requirements, impeller dimensions, and operating rpm by correlation equations; 3) considering effects of using larger cells, in necessarily much shorter rows, on process kinetics. The resulting seven tables that address these problems are presented, and their implications discussed.

Jan 1, 1999

By Reeves T. J, Hansen J. Y

Dense medium cyclone theory, supported by extensive experimental and plant-scale evidence, demonstrates that medium rheology (stability and viscosity) substantially affects cyclone performance in mineral applications.Two instruments have therefore been developed to allow medium stability and viscosity to be-monitored in the plant environment. The instruments are described, and examples are given of their application in full-scale plants.

Jan 1, 1989

By I. R. Kramer, H. Shen, S. E. Podlaseck

The tensile and creep properties of aluminum in vacuum have been investigated. It was found that the general effect of a vacuum environment was to reduce the rate of work hardening. Results obtained from creep tests showed that lowering the test pressure from 2 x 10-4 to 10-7 torr produced a decrease in the activation energy as much as 500 cal per mole. An attempt is made to explain these effects in terms of how the surface-stress field of a specimen may be affected by a vacuum environment during plastic deformation. In a previous paper,' the results were reported of some of our early work on the effect of vacuum environment on the stress-strain curve of aluminum single crystals. This effort has been extended to the studies of the tensile and creep properties in vacuum as a function of various metallurgical parameters. Some of the recent surface-effect studies2'3 have revealed that a region of high dislocation density, the so-called "debris" layer, is formed near the surface of the specimen as a result of plastic deformation. This layer acts as a surface barrier to oppose dislocation movement. The strength of this barrier depends on the surface condition such as oxidation or surface removal. Experimental results obtained from surface-removal work2, 3 indicate that such a surface barrier, which may be characterized by a stress field, affects the applied stress and the rate of work hardening. In the case of aluminum, this stress field was found to be directly proportional to the strain and the strain rate; however, the slope of this curve is independent of orientation of the crystal and may be altered by using different surface treatment. Since the escape of dislocations may be retarded by the presence of an oxide on the surface of a specimen, it is expected that a change in the rate of oxidation in vacuum will affect the process of dislocation accumulation in the debris layer. Consequently, it also affects the plastic behavior of a metal. This paper reports the changes in some of the creep and tensile properties of aluminum in vacuum and discussions of the observed effects in terms of the concept of the "debris" layer. EXPERIMENTAL PROCEDURE Tensile Tests. A sketch of the tensile apparatus is given in Fig. 1. This apparatus was contained in a bell jar (14 in. diam by 24 in. high) connected to a 10-in. vacuum system. The load was applied to the specimen by means of a gear train which was driven by a magnetic clutch located outside the vacuum chamber. The specimen, held by a pair of square shoulder grips, was attached to the load cell at the top and the drive gear at the bottom. A displacement transducer was placed between the two grips as shown in the figure to measure the elongation. Signals of elongation and load were amplified and recorded on an X-Y recorder. The system was capable of detecting loads as small as 0.025 lb and displacements of 0.0002 in. Shoulder-grip specimens of aluminum single crystals, having a nominal square cross section of 1/8 by 1/8 in. and a 3-1/2-in, gage length, were grown by the Bridgeman techniques. The original purity was 99.997 pet. The orientations of the crystals investigated are shown in Fig. 4(a). The crystals were annealed at 600°C for 2-1/2 hr, electropolished, and placed in the vacuum test chamber without any delay. All the crystals were deformed at a strain rate of 4 x 10-5 sec-1 at 24o ± 3°C. A study was made to find whether a chemically passive surface film would give the same effect as a vacuum environment. Specimens of aluminum 1100 (0.187 in. diam with a grain size of 0.1 mm)

Jan 1, 1965

By C. H. Elder

An experimental degasification program using a vertical borehole and vacuum pump to drain gas from the gob area of a longwall panel was successful at Bethlehem Mines Corporation, Cambria Division, No. 33 coal mine. Sixty-one million cubic feet of methane has been exhausted during a 9-month period. Daily production time in the panel increased as a result of lower methane levels in the returns. Removal of large quantities of methane in this way and the exclusion of it from the ventilating system will provide reduced cost in mine ventilation and provide a safer environment for the mine.

May 1, 1969

By Frank C. Appleyard

Gypsum, the dihydrate form of calcium sulfate, has a history of usefulness to man dating back several thousand years, and a worldwide industry has been built on the mining and processing of this versatile industrial mineral. However, anhydrite, the other principal calcium sulfate mineral has very limited use, so much so that separate statistics for it are not always kept, but are usually included with those for gypsum. Although often found in close association, the two minerals have important chemical differences in that anhydrite is the anhydrous form of calcium sulfate (CaSO,) whereas gypsum is the dihydrate (CAS0;2H20). These two molecules of combined water result in significant differences in hardness, density, and solubility of the two minerals. However, of most importance is the difference in thermal properties wherein gypsum, upon the application of a modest amount of heat, can be converted to the hemihydrate of calcium sulfate (CaS0;Vi H,O) or plaster of paris, an intermediate product upon which is based over 90% of the value of all calcium sulfate end products. Anhydrite, on the other hand, is inert at these temperatures and its uses have been limited to only those few cases where calcium sulfate in the anhydrous form may have an advantage. The earliest known use of gypsum plaster dates back some 5000 years to the time of the Pharaohs of Egypt who had discovered that gypsum rock, when exposed to fire, broke down into a powder which when mixed with water would form a putty that could be "plastered" on a rough mud brick or stone wall to make a smooth finish. It was used down through the centuries in a limited way for ornamental purposes, but did not achieve wide acceptance because of its quick (25 to 30 min) setting or hardening time which made it difficult to use. The first real understanding of gypsum chemistry was developed in France about 1755, and the gradual growth of its present utilization dates from that time. In the United States, the first utilization of gypsum was to grind it to a fine material for use as a soil conditioner at about the time of the Revolutionary War, and the term "land plaster" for ground gypsum has remained in use. Another cementituous material-lime or calcium oxide-had become the usual plastering material, but by about 1870 a method for retarding the set of gypsum plaster was discovered and it has today almost completely replaced lime as a plastering material. In recent years, gypsum products sold in the United States have reached a total valuation of approximately $500 million per year as illustrated in [Table 1].

Jan 1, 1975

By R. Drozd

"The Bullmoose Mine is currently under construction in the North East Coal area of British Columbia, and approximately $300 million will be spent to bring this 2.3 million-tonnes-per-year metallurgical and thermal coal mine into production by December 1, 1983.The project is an unincorporated joint venture undertaking, with Teck-Bullmoose Coal Inc., a wholly-owned subsidiary of Teck Corporation, holding 51%, Lornex Mining Corporation holding 39%, and Nissho-Iwai (Canada) Ltd. holding 10%. Bullmoose Operating Corporation will be the manager and operator of the project.This paper will broadly cover the history and exploration work on the property, the geology, open-pit mining plans and equipment, the preparation plant flowsheet from breaker station to clean coal silo, the 35 km highway truck haul, the railroad loadout system, manpower requirements, construction progress, approvals and permits, and general financial arrangements.IntroductionThe Bullmoose Mine Project"" is located about 87 road kilometres south of Chetwynd, B.C. and consists of an open-pit coal mine, a plant facility in the Bullmoose Creek valley below the mine, and a separate rail loadout facility on the British Columbia Railway Branchline near the new town of Tumbler Ridge some 35 road km to the east.The plant will be capable of producing a total of 2.3 million tonnes per year (mty) of washed metallurgical and thermal coal. Long-term metallurgical coal contracts for high quality, medium volatile, bituminous coal have been signed with nine Japanese buyers for 1.7 mty, and the balance of 0.6 mty will be thermal coal production.Plant construction began in the spring of 1982, and in May 1983, preproduction waste and overburden removal in the mine will commence. The plant should be fully operational by December 1983, and first vessel loading at the Ridley Island port is scheduled for January 1984."

Jan 1, 1983

By I. Filzwieser, S. Konetschnik, A. Filzwieser, A. Anzinger

Production in copper electrorefining tankhouses mainly depend on two factors: The deposition area, which is a result of the amount of installed cells and cathodes, as well as the current density - the amperage per square meter of deposition area. The present paper shows, that the most economical way of achieving a certain production is to maximize current density by using the METTOP-BRX-Technology - as building and infrastructure can be kept more compact. This industrial proven technology applies a parallel electrolyte flow in each electrolysis cell. In 2011, the first fully industrial applications started up: At the secondary smelter Montanwerke Brixlegg AG, 156 cells are equipped with the METTOP-BRX-Technology; this allows a current density of 390 A/m². Xiangguang Copper Co., Ltd. - a primary smelter and refinery - operates its new tankhouse (720 cells) at 420 A/m²; this stands for an production increase of 50% compared to the same sized ISA tankhouse which is limited to 280 A/m². The first part of the present paper gives a cost comparison between a conventional copper electrorefining tankhouse and a high current density tankhouse when assuming a Greenfield project. The second part describes the cost savings when installing the METTOP-BRXTechnology in an already operating tankhouse.

Jan 1, 2014

By T. P. Meloy

Improvement of grade and recovery requires the use of optimum processing circuits. Critical to an optimum circuit is the set point for separation. With the introduction of the concept of circuit analysis (Meloy, 1982), it became possible to determine optimum circuits for a given task. No analysis, however, has yet been made as to the grade requirements of the larger circuits. Williams and Meloy (1982), reviewed the literature and concluded that, within the operating range, most unit operations involved in particle separation behave linearly. For the purposes of this analysis, linearity will be assumed. Grade, G, is defined as the weight of the coal mineral, C, that appears in the product, divided by the weight of the coal mineral plus the weight of the gangue mineral or waste mineral, Q, which appear in the product.

Jan 1, 1982

By John C. Nigro

Bench scale and pilot plant research was conducted using dolomites (CaO,MgO) lime as the basic additive in the preparation of self-fluxed pellets from a typical magnetic taconite concentrate (5.57 S_2). The specific objective of this investigation was to ascertain the viability of the magnesia lime pellets in high temperature oxidizing and reducing atmospheres. Pellet basicity and induration temperature were major parameters affecting fired pellet quality; temperatures ranging from 1,200° to 1,250" C appeared to be the most favorable for production of self-fluxed pellets with basesities (B) above 1.0. Comparison of the mechani¬cal and metallurgical properties of regular (acid) and self-fluxed pellets (B 1.55) produced under similar conditions in a modified grate pelletizing machine showed that the self-fluxed pellets were more resistant to abrasion and to high and low temperature reduction disintegration, an important consideration in commercial application. The Plus 3 mesh Linder index increased from 68 percent (regular pellets) to over 90 percent (self-fluxed pellets). The reducibility and swelling indices of the self-fluxed pellets were found to be comparable to the regular pellets.

Jan 1, 1972

While mining silver at Butte in 1882, Marcus Daly is reputed to have told his partners in The Anaconda Silver Mining Co., "It looks rather gloomy. The vein is running into copper." Recently, The Anaconda Co. authorized an $11 million expenditure to be made over the next five years to ensure their "running into copper" at deep levels for many more years. The new development program is designed to permit both deeper and more widespread selective mining in "the richest hill on earth" by means of additional shaft-sinking, reactivating closed mines, and establishing new haulageways and centralized hoisting facilities. Historically a deep level selective mining camp, Butte will now continue its uncommon use of three main types of mining methods at one camp-selective mining, block caving, and open pit mining. It was thought by some people that the construction of the Kelley shaft and the subsequent beginning of block caving operations in 1952-outgrowth of the Greater Butte Project-signaled the end of stope mining of high-grade ores at depth. This feeling became more pronounced when, in 1957, the Berkeley open pit commenced operations. During recent years, the tonnage of ore mined selectively underground has decreased, but the new program will maintain the position of selective underground mining in the overall picture of the Butte operations for many years to come.

Jan 7, 1960

By Ernest L. Corp

The natural marine environment can be divided into four basic categories: the air-sea interface, the water zone, the seafloor, and the subbottom. Efforts are being made to accumulate data to delineate the conditions in each of these areas and to conduct engineering studies which will determine how these environmental parameters affect the mining process. Laboratory facilities have been constructed and equipment and techniques for scientific data collection and laboratory research have been developed. Major emphasis is being placed on studying the subbottom material. The objective of this emphasis is to study the engineering properties of marine placer deposits in order to assess their influence on the design and performance of the various mining subsystems involving penetration, excavation, transportation, and disposal. Presented are the results of engineering properties tests on a placer simulant which is currently being used for model and prototype testing of coring tools. The effect of these engineering properties on penetrability, core recovery, and sample recovery is discussed.

Jan 1, 1970

By Graham Jones

During 1982 Ash Grove Cement Company contracted with Wagester, Walker, Thornton & Company to convert a Calcimatic rotating hearth kiln at its Portland, Oregon lime plant from gas/oil to coal firing. Increasing costs of natural gas and No. 6 fuel oil made this conversion mandatory if the plant was to remain competitive. Unique features of this project are 1) the distributors of pulverized coal to eighteen small burners around the inner and outer perimeters of the doughnut-shaped kiln, and 2) the attrition-dryer-pulverizer mill. Ash Grove, a century-old lime and cement producer headquartered in Overland Park, Kansas (Kansas City area), looked at various schemes for multiple burner firing before employing Wagester, Walker, Thornton & Company. W.W.T. of Pitts- burgh, Pennsylvania was formed in 1980 by acquiring the Solid Fuels Division of the Pullman Swindell Corporation. This division had been active in developing solid fuel firing for brick tunnel kilns, principally in the Southeast. They continue to supply such systems firing wood waste as well as coal to the brick industry and have also converted two Calcimatic lime kilns for Dixie Lime, Sumterville, Florida, a fluid bed calciner for Texas Gulf in Aurora, North Carolina, and a chrome concentrate kiln for Diamond Chemicals at Castle Hayne, North Carolina. Testing and a proposal have been made for INMETCO, Elwood City, Pennsylvania, on an annular hearth furnace for direct reduction of iron ore to metallic iron.

Jan 1, 1984

By Y. H. Su, C. Y. A. Tsao

"The solidification behaviors and velocity of atomized droplets during flight is formulated by a mathematical model, in which the concept of transient nucleation is applied. During the flight, the droplet velocity shows a maximum, followed by an inflection phenomenon. The velocity of large droplet is lower than that of small droplet at shorter flight distance, and higher than that of small droplet at longer flight distance. The effect of the gas flow pattern is more significant at longer flight distance than at shorter flight distance at a given flight distance, large droplet has higher temperature than small droplets prior to nucleation. Large droplet has higher nucleation temperature than small droplet. Medium size droplet flies over the shortest flight distance before the nucleation starts. At the end of recalescence, large droplet has less solid fraction than small droplet has.IntroductionTraditional concept of steady state nucleation was used in all the previous models describing the solidification of molten droplets. [1-5] However, during atomization, the solidification rate of the molten metal droplets is very high, and therefore there is very little time for the nucleation event to occur. In the present work, the concept of transient nucleation [6] is considered to model such short nucleation event during solidification of the atomized droplets. The solidification behaviors and velocity of atomized droplets are modeled and the effects of the atomization gas flow pattern are also presented."

Jan 1, 1997

By G. L. Oldright

In an earlier series of 15 Reports of Investigations on Smelting in the Lead Blast Furnace, experimental data were given on the operations of a custom smelter, a smelter treating rich lead products, and a smelter treating highly zinciferous charges. Five "reports" were written on each of the three types of operation, which were later compared in a summary written for the Institute. Developments in each of these types of operation in lead smelting since the last of the above reports was written have continued and have followed modifications necessitated by changes in the nature of the products received for smelting. The sintering-blast furnace-smelting plants have improved their sintering operation .and have made "2-pass" sintering a more standard operation; the richer lead feeds are diluted when marginal precious metal ores are not available to prevent fusion of the sinter cakes and to permit air to contact the sulfides. Means have been devised to make it easier to remove metallic lead from the wind boxes, but no attempts have been observed to use the D & L somewhat as an ore hearth to make more metallic lead. Except in those cases where zinc-rich lead blast-furnace slags were to be retreated in a "slag-fuming furnace," the sintering and the blast-furnace operations were so carried out that a relatively "clean," lead-poor, final slag was discarded.

Jan 1, 1949

Frank H. Probert, A.R.S.M., Morenci, Arizona (communication to the Secretary): The management of mines and the system of bookkeeping employed are subjects of great interest to mine-superintendents, and such papers as that of Mr. Davis callnot fail to attract attention. The Institution of Mining and Metallurgy, London, England, has done much within the last three years to promote discussion on the many systems adopted throughout the mining world; and any papers giving individual experience will benefit that class of men who are charged with the cconomical management of mining properties. It is often said that " a good mine shows a good manager," and more often that mismanagement is the chief cause of poor returns; or, as Mr. A. G. Charleton puts it, in his able paper on " Mining Accounts and Cost-Sheets,"* " accident may, and often

Jan 1, 1902

This paper briefly discusses the negotia- tion of the more important provisions in agree- ments for exploration and mining rights with Pacific countries. LAND RIGHTS Land rights are complicated and sometimes controversial in many of the Pacific countries. In some countries, a company will have to deal with land owners directly; in others, the government will act as intermediary. Inevit- ably, a company will have to deal with both. Mining companies need to be sensitive to the culture and particular interests of the land owners and of their history in defending their rights. The issues are too complicated to be dealt with here. Some mining companies have spent, and will continue to spend, considerable time trying to understand them. It will " require patience, perseverance, sensitivity and unflagging optimism. The better advised companies will ensure that their local repre- sentatives get to know the land owners, under- stand their concerns, and will pursue a policy of keeping them informed on a regular basis of all of the company's activities and proposed activities. Good community relations are the keystone for good mining operations in the Pacific. Most countries will require the submission of an environmental impact statement so that they will know in advance what effects a pro- posted mining operation are expected to have on the environment and how it is intended to deal with them. They will also want to approve the company's environmental reclamation and rehabilitation plan. Let's face facts right away - mining, by its very nature, is not going to improve the environment. There will be waste discharges, emissions and deposits. They will affect the land, air and water and hence human, marine and animal life and vegetation. There will be sounds and odours and the esthetics of mining operations, though perhaps pleasing to geolo- gists and mining engineers, will not please Others.

Jan 1, 1987

By Lester C. Uren

Petroleum occurs, in nature, as a fluid saturating the pore spaces between the grains of porous rocks or aggregations of rock particles such as sand, sandstone, conglomerate, shale, limestone, etc. The oil, under the influence of gas pressure, hydrostatic pressure, gravity, earth pressure, and, perhaps, other natural forces, is caused to flow through the porous "reservoir rock1' into wells penetrating the stratum in which the oil occurs. The principal moving force is the pressure of dissolved or occluded natural gas within the oil, though this force is assisted by gravity and by the hydrostatic or buoyant pressure of ground water about the edges of the "pool." The wells, providing outlets to the surface, are centers of reduced pressure and the flow of rock fluids into a particular well is usually an expression of the difference in pressure existing between the space within the well and that of the stored oil within the reservoir rock. The greater this differential pressure, the more rapidly will oil flow from the source rock into the well. Opposing movement of the oil from the reservoir rock into the well are certain natural forces related to the rock structure, such as pore friction and capillarity, and certain others related to the physical properties of the oil, such as viscosity and adhesion. The differential pressure between the well and the boundaries of the area drained by it must be sufficient to overcome the forces opposing flow if there is to be movement of oil into the well. If by any device the resistance to movement of the oil may be reduced, the oil will flow into the well at a more rapid rate and the effective area of drainage will be increased.

Jan 1, 1925

Nickel-iron sulphide mineralization at Nepean, Western Australia occurs within a small Archaean greenstone outlier in granite south of the main Coolgardie greenstone belt. Individual sulphide ore bodies are situated near the foot- wall contact of simply-differentiated en echelon ultramafic sills that have intruded a sequence of sulphide-bearing metasediments and amphibo- lites. The paper describes a detailed section through the No. 2 ultramafic sill and its associated sulphide ore zone, which gave Metals Exploration N.L. the first significant nickel discovery in the Nepean area in 1968. The sill is variable in thickness up to 30 m along a strike length of 600 m, and is truncated to the north by pegmatite intrusion and pinches out to the south. The body has border zones of pyroxenetic composition, now represented by felted aggregates of chlorite and amphibole, and a central peridotitic core in which olivine and orthopyroxene are concentrated towards the base. Textures within the peridotite are dominated by large lath-shaped olivine grains and their serpentine pseudomorphs, which delineate triangular areas composed of talc, chlorite, and amphibole. Orthopyroxene occurs in large ovoid patches and is often replaced by Talc.

Jan 1, 1973

By Hebbard GJ

Vertical crater retreat mining is being used at Zinc Corporation, Limited and New Broken Hill Consolidated, Limited for pillar recovery between previously mined and filled stopes. In order to increase productivity in the older lead lode areas of the mine, particularly in the lower grade sections around the keel of the orebody, score form of longhole stoping was considered necessary.Due to poor ground conditions in the country rock surrounding the ore and the requirement to provide sane wall support during mining, primary VCR mining has been utilised in these areas.At Zinc Corporation, several stopes have thus far been mined by a hybrid longhole stripping - VCR method.

Jan 1, 1985