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By Wei Tu

A grade separation was required to allow uninterrupted traffic crossing for a busy rail spur and a county road. The grade separation was achieved by creating a 30-foot (9-meter) high embankment that incorporates two multiplate tunnels and allows the passage of a rail spur and an existing county road. The site is located in an abandoned meander channel in the floodplain of the Mississippi River, near Osceola, Arkansas, and is underlain by more than 40 feet (12 meters) of soft clay and interlayered clays, sands and silts. Without soil improvement, the post-construction settlement would exceed 3 feet, slowly crushing the proposed tunnel structure and cutting off the railroad. Preloading, combined with vertical drains, was used to accelerate the consolidation of the underlying soil layers and to reduce the post-construction settlement under working loads. Six settlement plates were installed to monitor the progress of consolidation under surcharge load. The Asaoka observational method and the hyperbolic fitting method were used to analyze the measured settlement data to predict the end of primary settlement. The in-situ consolidation coefficient, ch, was back calculated from the measured settlement data. The stress release caused by the removal of the preloading surcharge load and the tunnel installation was determined using a Plaxis 3-D finite element model. The measured and predicted settlement using Hansbo's analytical solution demonstrated reasonable agreement. Early removal of the surcharge and construction of the tunnel prior to reaching the end of primary settlement was accomplished by analyzing the post-excavation stress reduction achieved via tunnel construction.

Jan 1, 2009

By Ben M. Lewis, Yogesh Prashar

"The East Bay Municipal Utility District (EBMUD) is a major water utility service providing water to over 1.3 million people in the eastern San Francisco Bay Area. EBMUD manages 28 dams at 5 terminal and 23 open-cut reservoirs within a 331-square-mile customer service area. As part of a 2012 update on EBMUD’s Infrastructure Rehabilitation Plan for Distribution Reservoirs, EBMUD has decided to replace Central Reservoir, a 152.8 milliongallon open cut reservoir, with optimally sized tanks. This paper presents the results of an analytical comparison of various foundation reinforcement solutions for the proposed tanks including: Cement Deep Soil Mixed (CDSM) columns, vibro stone columns, rammed aggregate piers, and lightweight cellular concrete fill. The computational program GeoMat (www.ensoftinc.com) was used to perform simplified soil structure interaction analyses. Settlement estimates were developed for each alternative with the proposed loading and compared to an allowable differential settlement criterion established at 0.3-inches over a 50 foot length. The authors wish to present the importance of considering mat and soil interaction along with various settlement mitigation methods considered for this challenging project.INTRODUCTIONProject BackgroundCentral Reservoir is an operational open-cut reservoir located north of the intersection of 25th Avenue and East 29th Street in Oakland, California. The reservoir is bound by 23rd Avenue to the west, Sheffield Avenue to the east and Interstate Highway 580 to the north. Originally, the Central Reservoir site was a drainage swale incising into weathered bedrock formed from Pleistocene alluvial deposits. The reservoir was first constructed in 1910 by excavating a basin below grade and constructing an embankment dam on the south and cutting/filling the bedrock and alluvial deposits from the drainage swale. The main dam at the Central Reservoir site is also a DSOD (Department of Safety of Dams) jurisdictional dam and as such is regularly monitored by the EBMUD Materials Engineering Section and the California DSOD.In a 2012 update to EBMUD’s Infrastructure Rehabilitation Plan for Distribution Reservoirs, Central Reservoir was identified as a critical facility that has reached the end of its useful life and must be replaced due to: a failing panel craft lining which contains polychlorinated biphenyls in the interior coating, a roof that does not meet the current seismic code, and reduced operating levels due to potential leakage in the upper portions of the panel craft lining. Furthermore, Central Reservoir is about three times larger than required and is located at a lower elevation than other regional reservoirs in the pressure zone resulting in increased labor-intensive operational challenges and water quality operations.This project presents some challenging geotechnical demands – the site is founded on weakly consolidated Holocene Alluvium overlying weathered bedrock, the proposed structural loads are large, and the new Central Reservoir is to be placed on a pad at an elevation of 182 feet, required placement of up to 30 feet of fill over the current basin. Additionally, the project aims for a long-term foundation solution that will outlive the new replacement tanks and accommodate future site upgrades. In order to meet this goal, the differential settlement criterion for the tanks was ¼ inch over 50 feet length. Lastly, the project also aims to address EBMUD’s increasing trench spoil stockpiles by recycling discarded trench spoils as fill for the proposed tank pad."

Jan 1, 2016

By Richard A. Forth

During the construction of the Island Line (ISL) in Hong Kong between 1982 and 1986 piled foundations of a building were encountered in a tunnel drive. As the tunnel alignment could not be changed work was temporarily suspended whilst grouting took place beneath the pile cap. The tips of the piles were then cut off. The normal precast concrete lining segments were replaced by the "stiffer" spheroidal graphite iron segments and tunnelling resumed. Settlement of the building was found to be under 10 mm due to the tunnel drive and no damage was reported to the building.

Jan 1, 2002

By J. Don Scott

Analytical predictions of the rate and magnitude of settlement of deposited oil sands tailings slurries generally overestimate how fast pore pressures will dissipate. Field deposits of nonsegregating tailings to mature fine tailings show continued high pore pressures near the surface which impede surface reclamation. In geotechnical analyses which predict the consolidation behavior of soft soils a finite strain theory is used. Effective stress-void ratio and void ratio-hydraulic conductivity relationships determined from laboratory large strain consolidation tests, are used in the finite strain predictions. This theory, however, cannot predict the full range of sedimentation, consolidation and pore pressure dissipation which occurs in large scale deposits of thixotropic tailings slurries. A new large strain consolidation model which assumes that the creep rate of the slurry exceeds the pore pressure dissipation rate is being investigated. This model is relevant for rapidly deposited, low permeability thixotropic slurries where the upwards drainage path increases by several meters a year, such as, in oil sand fine tailings ponds and nonsegregating tailings deposits. The model will be verified by analyzing the 10m high column of fine tailings at the University of Alberta which has been monitored for over 20 years and in which the excess pore pressures are still very high.

May 1, 2004

By Rudolph P. Frizzi

This paper presents different deep foundation systems and associated settlement records for high-rise building projects in the coastal areas of southeastern Florida. An introduction to the sedimentary soil and soft rock geology in coastal areas of southeast Florida is presented, and the deep foundation systems utilized include: piles of varying length, pile supported mat, preload and short piles, and drilled shafts. The implementation and associated settlement monitoring data of the different deep foundation systems are described through case histories involving 20 to 66-story buildings. In addition, the deep foundation systems and settlement monitoring results for twenty-one additional high-rise building projects in the coastal areas of southeastern Florida are presented.

Jan 1, 2003

By Swaminathan Srinivasan, Aaron J. Muck

"When an opportunity arises to combine state-of-the-art concepts with advanced modeling tools, engineers need to take what they know and apply forward thinking to geotechnical solutions to promote the state-ofpractice. Such an opportunity was seized during the design and construction of the Great American Tower in Cincinnati, Ohio. The forty-one story Great American Tower at Queen City Square – currently the tallest building in Cincinnati – has not only changed the downtown skyline, it is also contributing to the advancement of the state-of-the-art use of auger cast-in-place (ACIP) piles as settlement reducers. Predicted settlements of a traditional mat foundation were excessive, and the costs and construction time associated with traditional ACIP piles extending to bedrock were not preferred. A mat supported on a limited number of ACIP piles, with the piles primarily acting as settlement reducers, was evaluated as the preferred foundation type.Promoting the unique soil-structure interaction of the foundation system with confidence required the use of sophisticated numerical modeling tools. Traditional standard penetration test boring data (SPT) was initially used to develop a numerical analysis of the soil-structure interaction using FLAC 3D software. The model was further modified with cone penetration (CPT) and pressuremeter testing (PMT), along with actual load test results on several ACIP pile elements of varying lengths, but all tipping above bedrock. Through a combined design team effort, and detailed numerical modeling analysis, ACIP piles were recommended for reducing mat foundation settlement. Instrumentation during and post-construction confirmed design assumptions and predictions. Integrating sound geotechnical concepts, and using advanced geotechnical analysis and design methods, traditional mat and ACIP pile foundations were successfully integrated into a unique foundation support system.INTRODUCTIONThe Great American Tower at Queen City Square in Cincinnati, Ohio is located within a region dissected by historical geologic deviances associated with the meander of the Ohio River and glacial progression/recession. Combining a challenging geology, with the development of a high-rise office building afforded the design team an opportunity to combine state-of-the-art soil-structure interaction concepts and method with traditional geotechnical engineering concepts. Such a combination required a variety of field tests, collaboration with the design team and owner, and geotechnical-structural modeling during the design phase. During construction, in addition to materials testing and observation, a variety of instrumentation systems were employed. Together, the data was used to corroborate the design model and make adjustments during construction and further substantiate design assumptions following construction."

Jan 1, 2015

By Jan Steinhoff

The design options of a gravity separator are still limited and rely on the study of settling behavior. A methodology will be presented where an experimentally given inlet droplet size distribution (DSD) is the basis for the calculation of the dispersion layer in a gravity separator. A pilot-scale continuous gravity separator is presented and CFD (computational fluid dynamic) results are validated. A transmitted light measurement technique for the determination of the DSD is presented up to a holdup of 15% dispersed phase. The resulting DSD was in the range of 20–2000 μm depending on flow rate and phase ratio. Furthermore, correlations of the real DSD with the settling behavior of the dispersion in a settling cell are discussed. The new approach to the description of gravity separators will be presented and the applied CFD methods showed good results with the system water/paraffin.

By Lucas Nana Wiredu Damoah, Lifeng Zhang

"Increasing demand for Solar Grade Silicon (SoG-Si) due to rising interest in renewable energy has lead to increased SoG-Si Top – cut scraps generated from the multi-crystalline silicon making process. Due to the high cost of SoG-Si and the potential to use the top-cut scraps as feedstock material, there has been increased effort to develop cost effective and efficient technologies. As a result, several methods to recycle the top-cut scraps are currently been applied, and researched. These include settling under gravitation field, which is a slow process to be industrially applicable. Natural settling of inclusions by gravitational force is a slow process and not attractive to the industry. Recent experiments on Top-cut SoG-Si scrap under high frequency, high voltage, electromagnetic field showed that SiC inclusions settled within a short time to the bottom of the crucible and the characteristic rod-like morphologies of Si3N4 inclusions in SoG-Si were not detected. This study investigates the enhanced settling of SiC inclusions and the behavior of Si3N4 particles under the influence of high frequency, high voltage, electromagnetic field in Top-cut SoG-Si.IntroductionThe photovoltaic industry depends on silicon based PV materials either as single-crystalline silicon, or multi-crystalline Si (MC-Si), or amorphous Si [1] for over 90 % of its market share. [2] MC-Si produced by directional solidification of solar grade silicon melt dominates the silicon PV market. During the directional solidification process, SiC and Si3N4 particles within the melt are pushed by the solidification front to the top of the ingot which is the last to solidify. Therefore the top of the ingot is cut generating what is known as top-cut solar silicon scraps. The Si3N4 particles are mainly from the coating material at the inside surface of the silica crucible and from air absorption during the solidification process. The SiC particles mainly stem from the carbon reduction process of the primary production of silicon [3]. Due to the growth of the PV industry as a result of global demand for clean, reliable, and affordable energy [4], there is the need to develop new methods to compliment exiting ones to recycle SoG-Si waste (e.g. top-cut) for sustainability."

Jan 1, 2012

By H. L. Monroe

Meramec Mining Company, owned 50% by St. Joseph Lead Company and 50% by Bethlehem Steel Corporation,- is engaged in the mining, concentrating and pelletizing of iron ore from the Pea Ridge Mine which is located in the rugged, wooded Missouri Ozarks about 15 miles from the town of Sullivan or 75 miles southwest of St. Louis. The orebody was delineated in the middle 1950's by the St. Joseph Lead Company during the Company's intensive exploration program to discover new lead orebodies to replace the declining reserves of the famous Southeast Missouri Lead Belt. An airborne magnetometer survey was run by the U.S. Geological Survey, the Missouri Survey and several mining companies, (of which St. Joseph Lead Company was the principal supporter). The survey was published in 1950 and disclosed an anomaly in the vicinity of Pea Ridge. In 1950 test drill holes disclosed that under some 1300 feet of sediments there did exist an iron deposit of probable commercial significance. No further action was taken until 1956 when additional drill holes confirmed beyond reasonable-doubt-that this was a major iron ore discovery.

Jan 1, 1965

By J F. Seale

The design of the settling pond for the Malvern Hills opencast coal project was based on a primary requirement to control runoff and sediment generated from the immediate 6 ha mine catchment, which included two seepages from old underground workings. The pond has been particularly effective in controlling turbidity in the outflow water, with the consent limit of 50 NTU being met on all but one occasion and normal levels of discharge less than 10 NTU. Water quality testing carried out at the time of consenting indicated that there were no acid-generation issues with the proposed mine site in dominant mudstone strata of the Broken River Formation, and that water from the old mine workings was near-neutral in terms of pH and well-buffered. However, it became apparent over the very dry summer of 2003 - 2004 that slaking of the exposed mudrocks in the mine batters was resulting in significant acidity generation, and outflow pH levels were well below the consent limit of 6.5 during and following periods of rainfall. Although these acidity problems have been remediated in the short-term by the use of lime products, it is clear that a programme of lithotype characterisation for AMD should have been undertaken and this has now been implemented. Design of long-term acid drainage control measures is being carried out, and will probably be based around the use of hydrated lime for pH control with enhancement of natural wetlands.

Jan 1, 2004

By A. K. Majumder

Particle motion in fluids is a subject of considerable practical importance to engineers working in fields such as hydraulics, river mechanics, chemical engineering and mineral processing. Many mathematical models have been proposed to predict the terminal settling velocities of particles in a fluid medium. The selection of an appropriate mathematical model has, therefore, become a challenging task for practicing engineers. This paper reports on an attempt to identify some of the useful models found in the literature for predicting particle-settling velocities in a fluid under free- and hindered-settling conditions. From this study, it was concluded that there is no well-accepted model validated by experimental data available for predicting particle hindered-settling velocities in a suspension of polydisperse and polydens particles. Collective efforts should, therefore, be made towards developing a hindered-settling model, as this is an absolute prerequisite for many model structures in mineral processing and other engineering disciplines.

Jan 1, 2007

Jurist, educator and historian Neil Reynolds will be the keynote speaker at the National Mining Hall of Fame's 11th annual induction banquet on Sunday, Oct. 11,1998 at the Pointe Hilton Resort in Phoenix, AZ. Reynolds is Municipal Court Judge for the City of Leadville, CO, home of the National Mining Hall of Fame & Museum, and a fifth-generation resident of the community. His family staked mining claims on nearby Mount Massive in 1862. Judge Reynolds is a fulltime faculty member at Colorado Mountain College, Chairman of the Lake County Historic Preservation Advisory Board and practices law in Leadville. In announcing the speaker, Board Chairman Richard Moolick said seven inductees into the National Mining Hall of Fame will join 138 mining greats previously honored in the annual ceremonies. This year's inductees will be enshrined by Thomas Falkie, president and chief executive officer of Berwind Natural Resources of Philadelphia, PA. Moolick also announced that Jeffrey Clevenger will be the master of ceremonies for the induction banquet. Clevenger is executive vice president of Cyprus Amax Minerals, Englewood, CO and president of Cyprus Climax Metals, Tempe, AZ. A cocktail reception at 6:30 p.m. will precede the black-tie (optional) dinner, to begin at 7:30 p.m. For additional information, contact Esther Mellott at 719 486 1229. Here are the biographies, then, of this year's seven inductees to the National Mining Hall of Fame & Museum.

Jan 1, 1998

By C. D. King

THIS year the American Institute of Mining and Metallurgical Engineers celebrates its seventy-fifth anniversary as well as the same anniversary of iron and steel in this country as we now know it. The society's span of life comprehends the very beginning and gradual development of the present-day iron and steel industry and its TRANSACTIONS are rich with the trials and achievements of the pioneers in this field. It is difficult to believe that in the first year of the Institute's existence there was produced in this country only 84,000 net tons of ingots, of which only 2000 tons was made by the open-hearth process; that the bessemer process was just barely beginning; that charcoal and anthracite were virtually the only blast-furnace fuels; that Mesabi ores had not been used in blast furnaces, and such pig iron as was then made was produced at a number of small units, each adjacent to its ore and fuel supply. The growth from 84,000 net tons production of steel ingots to 95,500,000 tons in 1945 eloquently tells the story of America's industrial growth.

Jan 1, 1947

By Oliver Bowles

Two striking events marked the year 1871-the establishment of the A.I.M.E. and the beginning of the portland cement industry, the most spectacular of all the nonmetallics in its development. Just as David Saylor's first portland cement, made in a little mill at Allentown, Pa., in that year was the forerunner of a mighty industry, the products of which in 1942 were made in 155 plants scattered throughout the country (having attained a value of nearly $300,000,000), so the Institute from its small beginning has attained a membership of many thousands, likewise decentralized into a series of individual sections of wide geographical distribution. Concurrent with the establishment of the Institute was also the invention of the steam drill, followed by the compressed-air drill about 1904. These mechanical drills were so immeasurably in advance of the hand drill and hammer used previously that quarrying and mining of present-day magnitude could never have been attained without them. Some outstanding occurrences have marked this eventful three quarters of a century. The concrete age, with its enormous demands for cement, aggregates and steel, is of primary importance. Of interest also is the shift of fertilizers from the organic to the mineral field. Nitrates, primarily obtained

Jan 1, 1947

This article updates the status of fatalities occurring in both coal and metal/nonmetal mines from January through December of 2001. Based on preliminary accident reports, as of December 31, 2001, seventy-two fatalities have occurred at coal and metal/ nonmetal mining operations. During this period, forty-two fatalities occurred at coal operations and thirty fatalities occurred at metal/nonmetal operations. Ignition or explosion of gas or dust and fall of roof were the most frequent accident classifications in coal and powered haulage fatalities were the most frequent accident classification in metal/nonmetal.

Jan 1, 2002

Several Approaches to Enhance the Bioleaching of Enargite Some approaches were investigated to enhance the recovery of Cu from enargite by bioleaching with Acidithiobacillus ferrooxidans using the galvanic interaction with pyrite and activated carbon, and with thermophilic bacteria, Acidianus brierleyi. Addition of pyrite initially enhanced Cu leaching by the Galvanic effect, but after that the formation of secondary minerals passivated the surface of enargite in inoculated batches. Activated carbon improved Cu recovery from enargite much better than pyrite, when it is contacted with enargite. Recovery of Cu from enargite has been recorded to at largest 2.4 per cent within 30 days in the presence of activated carbon when mesophilic bacteria were inoculated at 25¦C. The recovery of Cu from enargite was drastically enhanced by inoculation of thermophilic bacteria, Acidianus brierleyi, up to 60 per cent within 40 days at 70¦C and still not leveled off after 40 days unless the formation of Fe(III) precipitates occurred. After 40 days dissolved molar ratio of Cu/As is around 5.2, suggesting that metal-deficient sulfides and/or ferric arsenate might be formed on the surface of enargite.

Sep 13, 2010

China has made great progress in thick coal seam mining, commonly characterized by longwall top-coal caving mining and single-pass longwall mining with a large cutting height. At present, the maximum mining thickness of longwall top-coal caving reaches 20 m while that of single-pass longwall mining approaches 8.8 m. The top-coal caving–related technologies have significantly improved the mining efficiency of thick coal seams and have also made a great contribution to the centralized underground mining of coal. Thus, the number of underground coal mines is greatly reduced in China. However, due to the increase of the mining height and the changes in mining operations, the overburden movement caused by the mining of thick coal seams is more intense, and the influence scope is larger, which brings a series of new problems on ground control of longwall faces. In order to enhance ground control and improve the mining efficiency of thick coal seams

Jul 28, 2020

By William R. Bond

The pressure/vacuum lysimeter is being used as an effective vadose zone monitoring device for mining heap leach facilities, tailing disposal ponds and tailing waste sites. Their use has proven reliable for baseline data collection, early warning leakage detection and analyzing geochemical variations in the vadose zone. The lysimeter structure utilizes a closed cylindrical chamber made of PVC or inert material. The soil water intake portion of the cylinder is made of a porous material of low permeability. The application of vacuum or pressure to the unit is via two access tubes from the ground surface. Available soil moisture is drawn by vacuum through porous material into the lysimeter chamber and then collected from the access tubes. Case studies show their usefulness for monitoring around a uranium tailing pond constructed in glacial till material, under heap leach pads and pregnant, barren, and overflow ponds, and investigating the movement of contaminant moisture through old tailing deposits. Relatively easy to install and sample, regulatory agencies and facility operators are accepting and negotiating for their application as a site integrity monitoring device and unsaturated zone research tool. Their use at heap leach facilities lends credibility to solution balance calculations when considering a leachate loss of 5 or 10 percent can make or break a mine's profitability.

Jan 1, 1984

By M. Pearson, J. Irvine, L. Mercer, P. Lauzon

Severe service ball valve performance has a direct impact on the mechanical availability of high pressure oxidation and leach plants. The primary function of these valves is to isolate the autoclave for maintenance. Valve failure has historically contributed significantly to the maintenance downtime of these process plants. An understanding of the root causes of valve failures is the first step in increasing the reliability of the severe service ball valves. A rigorous failure analysis practice has been developed by Hatch for investigating refractory failures in furnaces and kilns based on Kepner-Tregoe methodology. The method has also been modified for valve failure analysis. From a root-cause failure tree analysis of each of the valve components, a list of all potential valve failure mechanisms was developed for ranking and evaluation, along with recommendations for further valve development. The purpose of this paper is to present the reader with the modified Kepner-Tregoe method and examples of this analysis.

Jan 1, 2004

By G. R. Waters

"The technology behind industrial applications such as Hydrometallurgy continues to evolve, as do the corresponding regulations and specifications that ensure the safety of workers and the environment. Valves make up key aspects of this technology, and often represent the single point of failure for entire operations. More often than not, the valves being used in Hydrometallurgy applications are known as Severe Service Valves (SSVs) due to their ability to withstand the extreme conditions. Most experts agree that SSVs are identified by applications, and that these applications are challenging to the valve’s ability to provide a minimum acceptable level of performance over a minimum acceptable duration. The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry has designated Ross Waters, President of CGIS, as Lead to the Task Force put in place to determine the minimum requirements a valve needs to be able to perform to when faced with extreme conditions, whether from pressure, temperature, toxicity, solids, or usage. This paper serves to determine what the minimum requirements are for SSVs in Hydrometallurgy applications. It will draw on five decades of industry experience from one of Canada’s leading valve experts.INTRODUCTION Severe Service Valves Severe Service Valves (SSVs) mean different things to different people. Until today, defining SSVs had little if any global agreement or recognition. That is about to change as the Manufacturers Standardization Society (MSS) has accepted an application to produce a Standard Practice so defining them. This paper provides information about the selection of SSVs in all industries but focusses on metallurgical processes and applications and offers examples to illustrate the successful and unsuccessful use of these valves. All of this with the purpose of raising the awareness of the industry on all sides, from the suppliers and manufacturers, specifiers and to the users and owners of them. It also supplies tools to understand where and why to separate SSVs from general purpose or commodity valves (GPVs). SSVs are often identified by applications, and these applications are challenging to the valve’s ability to survive. Within these applications the elements that make the service severe are being analyzed, quantified and qualified. From this, we expect to offer objective and repeatable definitions and guidance to improve the experience of SSVs, reduce unnecessary costs, provide longer service life and process runs, improve safety and reduce environmental issues."

Jan 1, 2017