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By Mohamed Mekkawy, William W. Wheaton, Ira Brotman

"The Virginia Port Authority and the U.S. Army Corps of Engineers are partnering to construct the Craney Island Eastward Expansion (CIEE) to meet the dual purpose of extending the life of Craney Island as a dredged material management area and providing land for a state-of-the-art marine terminal. The over 500-acre (200-hectare) expansion provides additional upland dredged material capacity for the Hampton Roads Harbor by constructing perimeter dikes, that once filled, will provide land for the development of a container terminal. In the winter of 2010/2011 the first stage of sand fill was placed, followed by the installation of approximately 12 million linear feet (MLF) (3.6 million linear meters, MLM) of marine PVDs. With over 36 MLF (10.9 MLM) of PVD required to complete dike construction the project will be one of the largest PVD installation project in the U.S.This paper details the challenges associated with the construction of the cross dikes, in particular the design, testing, installation and monitoring of prefabricated vertical drains (PVDs) installed overwater to depths of over 130 feet (40 meters) for foundation improvement in the insitu very soft Norfolk Clay. With expected settlements of 20–30 ft (7-10 m) and 30 percent average strains, the discharge capacity of the PVDs was of particular concern. Laboratory data is presented showing the magnitudes and variability of discharge capacity under different confining pressures in both a straight and buckled condition.The method of installation and monitoring of the marine PVDs in open water included developing a specialized barge and sophisticated positioning and data collection system to verify installation location, depth of penetration and track quantities. An observational method, including material testing, detailed surveys, periodic in-situ testing, and instrumentation, was utilized by the project team to assess the project’s progress and allow for validation of consolidation and strength gain rates and magnitudes."

Jan 1, 2017

By Ira Brotman

The Virginia Port Authority and the U.S. Army Corps of Engineers are partnering to construct the Craney Island Eastward Expansion (CIEE) to meet the dual purpose of extending the life of Craney Island as a dredged material management area and providing land for a state-of-the-art marine terminal. The over 500-acre (200-hectare) expansion provides additional upland dredged material capacity for the Hampton Roads Harbor by constructing perimeter dikes, that once filled, will provide land for the development of a container terminal. In the winter of 2010/2011 the first stage of sand fill was placed, followed by the installation of approximately 12 million linear feet (MLF) (3.6 million linear meters, MLM) of marine PVDs. With over 36 MLF (10.9 MLM) of PVD required to complete dike construction the project will be one of the largest PVD installation project in the U.S. his paper details the challenges associated with the construction of the cross dikes, in particular the design, testing, installation and monitoring of prefabricated vertical drains (PVDs) installed overwater to depths of over 130 feet (40 meters) for foundation improvement in the insitu very soft Norfolk Clay. With expected settlements of 20?30 ft (7-10 m) and 30 percent average strains, the discharge capacity of the PVDs was of particular concern. Laboratory data is presented showing the magnitudes and variability of discharge capacity under different confining pressures in both a straight and buckled condition. The method of installation and monitoring of the marine PVDs in open water included developing a specialized barge and sophisticated positioning and data collection system to verify installation location, depth of penetration and track quantities. An observational method, including material testing, detailed surveys, periodic in-situ testing, and instrumentation, was utilized by the project team to assess the project?s progress and allow for validation of consolidation and strength gain rates and magnitudes.

By Martin Grenon

This paper presents two case studies where fracture set orientation was quantified using three methods: a simple fracture pole grouping, a Fisher distribution and a Kent distribution. The three fracture orientation representations were then used as inputs for kinematic slope stability analysis. Differences showed up in the probability of sliding for all instability modes considered.

Aug 1, 2013

By L. van Hijfte, A. Piché

"Drilling and blasting are fundamental operations in the mining cycle and constitute an important component of the mining costs. Problems associated with improper drilling and blasting practices can create losses of several millions of dollars per year. For this reason, a Blasting Technology program was initiated in 1984 at the Noranda Technology Centre (NTC). In this paper, advances made at NTC in drill and blast technology are reviewed. Impacts of drilling and basting for Noranda are assessed in terms of dilution and ore losses. Future challenges are addressed. IntroductionUp to 1997, Noranda was a diversified natural resources company that operated in three sectors: mining and metallurgy, forest products, and oil and gas. The company employs more than 33 000 people in operations and sales offices around the world. Today, Noranda has returned to its roots in mining and metallurgy. The new vision of Noranda is to be dedicated to the responsible and profitable development of mineral resources around the world for the benefit of its shareholders. In so doing, Noranda will continue to be deeply committed to the environment, health, workplace safety, cost competitiveness and return on capital. Technology is an integral part of Noranda’s success strategies. For this reason, the Noranda Technology Centre, formerly known as Noranda Research Centre, was founded in 1963. Since then, it has undergone four expansion phases to keep up with the increasing needs of the businesses. Today, NTC employs more than 220 specialists who work in partnership with different Noranda companies to identify, develop, and transfer technology to the operations, as well as to explore new sectors of activity."

Jan 1, 2000

By Benjamin W. Haynes

This Bureau of Mines publication comprises a compilation of the state of the science in Pacific Ocean manganese nodule mineralogy and elermental composition. The report is divided into three sections: morphology, mineralogy and elemental composition. The nodule morphology section defines what is considered a nodule for the study, and details the external characteristics and internal structure. Nodule mineralogy is discussed in three sections: manganese minerals, iron oxide minerals, and accessory minerals. The major manganese minerals discussed are todorokite, birnessite, and vernadite. The iron oxide minerals are less well known and include feroxyhyte, goethite, and lepidocrocite. Accessory minerals present include quartz, clays, and other silicates and nonsilicates. A discussion on moisture content is also included. The elemental composition section presents data on 74 elements occurring as cations or anions. Summary data, histograms, and interelement correlation coefficients are presented. The elements are grouped as follows: major and minor elements of potential economic interest (8), other major and minor elements (9), elements of environmental interest (8), rare-earth elements (15), precious-metal-group elements (6), radioactive elements (3), other trace elements (17), and anion-forming elements (8). Cross sectional determinations of Ni, Cu, Zn, Co, Pb, Fe, Ce, and Ba are given for a single nodule to show the general tendency of different growth patterns within a nodule because of different element associations and composition.

Jan 1, 1982

By Paul H. Johnson

Resource Engineering and Development, Inc. is designing and building a portable 150 to 225 TPD, flotation-cyanide leach plant with unitized, skid-mounted components. This plant design, with its portability, low capital investment, and high recovery of silver and gold from many partially oxidized ores, is well suited to treat many small, high-grade deposits, old waste dumps, and old mill tailing piles. A description is given of flotation and/or cyanide leach tests run on about 17 partially oxidized, newly mined ores; waste dump materials; placer slimes; and old mill tailings.

Jan 1, 1981

By M. F. Goodrich

The concept of using water-only cyclones as a clean coal scalping device preceding a heavy media cyclone circuit shows considerable promise, as it can considerably reduce the feed to the heavy media cyclone circuit. The system will not perform as well as a heavy media cyclone circuit alone, but the resultant loss in yield is small and may be negligible under some conditions. The concept of water-only cyclone scalping has previously been suggested by others. By reducing the amount of raw coal to be processed in the more expensive circuits overall capital and operating costs may be reduced. There are a few commercial plants with circuits operating on this concept. In the Warwick and Rowland plants water-only cyclones are used to scalp the feed to a heavy media vessel and Deister tables respectively while Amherst Coal Company's McGregor plant uses them to scalp the feed to a heavy media cyclone circuit. The system was evaluated on a technical basis, both from a theoretical viewpoint and by analysis of a computer simulation, in order to gain a fuller understanding of its usefulness and limitations.

Jan 1, 1977

By Chris Twigge-Molecey, John Peacey

To meet the business objectives of a metallurgical project, there is often a need for new and untried technology or equipment, whose very novelty can present serious risks to meeting those objectives. The key risk management approach is a rigorous stepwise progression from theoretical evaluations and laboratory tests to pilot plant trials. These must be followed by demonstration-scale trials before final construction of a commercial scale plant, paying particular attention to the magnitude of the scale-up between phases. Success depends on following a well-defined program, not eliminating any steps, and ensuring adequate resources are available to the development team. Chapter 6 discusses the nature of technology risks to metallurgical plant projects, and the rigorous management practices needed to identify, analyze, evaluate, and avoid or mitigate them.

Jan 1, 2015

By Roy L. Soderberg

Ground support for metal, nonmetal, and coal mines was examined through fill placement with a pneumatic stower to increase extraction, reduce ground pressures, and improve general mine safety. Several pneumatically stowed stope-fill products were tested to determine the effects of specific gravity, gradation, moisture, and impact velocity on the in-place density of the stowed fill. Hydraulic sand filling has now served the mining industry for several decades but because of the low density does not always provide ample support to the hanging wall; therefore, the sill and crown pillars sometimes build up excessive stresses that are detrimental to mining. Cementation of a dense fill adjacent to a pillar to allow 100-pct extraction of the pillar, or a fill that can be placed without the use of water and where water is a detriment to rubber-tired mining equipment, was found to be a possible use of pneumatic fill. Placing of coal mine washery products into abandoned underground workings is another possibility in order to completely eliminate surface impoundments.

Jan 1, 1976

By John J. Sammarco, Alan G. Mayton, Elaine N. Rubinstein

Researchers from the National Institute for Occupational Safety and Health (NIOSH) developed a light-emitting diode (LED) area luminaire called the Saturn and conducted a laboratory study using a Fletcher High Dual-boom Mast Feed (HDDR) roof bolting machine. The Saturn luminaire was designed to (1) enhance floor illumination to enable better detection of trip hazards in the interior spaces of a roof bolter and (2) reduce glare that has typically been an issue of concern on roof bolters. This paper reports on the results of achieving the second objective. The existing roof bolter lighting was the baseline and was compared with three versions of the Saturn luminaire relative to light intensity (100%, 75%, and 50%). Discomfort and disability glare data were obtained from 30 participants that comprised three age groups. Discomfort glare perceptions were obtained using the De Boer rating scale, and disability glare was quantified by using Mars Letter Contrast Sensitivity tests. Discomfort glare was reduced at least 3 levels with all Saturn versions. Also, a predictive model was used to estimate discomfort glare, and the results were similar. Disability glare was the least for the Saturn’s 50% intensity, and all Saturn versions had significantly less disability glare than with the baseline lighting. Veiling luminance was calculated and used as another indicator of disability glare. Veiling luminance was 28 to 42 times greater with the baseline lighting as compared with that of the Saturn lighting. Lastly, visibility levels were calculated. The Saturn versions were 4 to 6.5 times better in terms of visibility level.

By Yi Luo, Jian Yang, YUJIA LIAN

Scale physical models, constructed according to the principle of similarity theory, have been widely used to simulate the mining disturbances to surrounding strata and to evaluate the effectiveness of implemented ground control techniques. This technique has also been used for studying mining-induced surface and subsurface subsidence. The movements of the observation points installed on the physical model at different mining stages are currently measured using total station which is time-consuming and inaccurate especially on small scale models. A photogrammetry-based measurement system has been developed. During a physical modeling process, photos of the model can be taken during the simulation process reducing survey time from hours to a few seconds. A program, Photogrammetry Analysis for Physical Modeling of Mine Subsidence Process (PAPMMSP), developed based on photogrammetric principle is used to quickly identify the installed observation points and accurately determine their coordinates. The measurement accuracy is well under submillimeter level—an ultra-important advantage as any measurement errors in coordinates are magnified by the model dimension scale (commonly 20 to 400). A physical modeling case of subsurface strata movements and deformations associated with longwall mining operations is presented in the paper to demonstrate the functions and capabilities of the developed photogrammetry program.

Aug 11, 2020

By Charles M. Wilk, Lori Tiefenthaler

"Information presented in this paper can be used to support deep soil mixing, subsurface grouting and slurry wall technology as sustainable construction technologies. Ordinary Portland Cement (OPC) is the default cementitious material used by Deep Foundation Institute (DFI) Members for geotechnical work. Owners, engineers and contractors can contribute to the sustainability of a geotechnical project by increasing the use blended hydraulic cements and industrial byproducts to replace some of the OPC in mix designs. Sustainability is defined as the quality of not being harmful to the environment or depleting natural resources. Production of cementitious materials consumes natural raw materials and energy while also generating air emissions and waste. Life Cycle Assessments can be used to compare the relative environmental impacts of one cementitious material to another. Blended hydraulic cements (BHCs) are interground (or blended) mixtures of Supplementary Cementitious Materials (SCMs) with OPC. Commonly used SCMs include fly ash, ground granulated blast furnace slag (GGBFS) and limestone. Examples of industrial byproducts commonly used in geotechnical work include coal combustion residuals (CCR) (aka fly ash), and ground granulated blast furnace slag (GGBFS). Much of life cycle impact of these SCMs and industrial byproducts have already been borne by the industries that generated them. There is increasing awareness to LCA and sustainability of different materials used on projects. This is evident in the application of the Leadership in Energy and Environmental Design (LEED) program. The savings in environmental impact with the use of SCMs and industrial byproducts can make proposed use of these materials in a geotechnical project more attractive in terms of sustainability. This paper presents (a) information that compares published life cycle assessment data of OPC, BHCs, and slag cement (SC) to illustrate the potential benefits to sustainability and (b) general strategies for positioning a geotechnical application, use, project design or cementitious material mix as a more sustainable alternative"

Jan 1, 2017

By Manuel M. Reyes, Thuraisamy Thavaraj, Alex Sy

"The new east span of the San Francisco-Oakland Bridge features a single tower self-anchored suspension (SAS) bridge. During construction of the SAS bridge, a temporary bridge was used to support the box girders until erection of suspension cables was completed. The transfer of deck load from the temporary bridge to the suspension cables was achieved in November 2012 and the SAS bridge has become the largest of its kind in the world. The new bridge will be in service in Fall 2013.Large diameter driven steel pipe piles were used for the temporary bridge foundations at Towers D, F and G located in San Francisco Bay. At Tower D, the large diameter steel pipe piles were driven through thin overburden into bedrock using a large Menck MHU500T hammer with a rated energy of 550 kJ. As there was no precedence in driving open-ended pipe piles into the Franciscan Formation bedrock, challenges were faced with uncertainties in drivability, driving stresses, pile embedment in bedrock and pile capacity. These uncertainties were addressed by incorporating additional measures into the pile design, and by the use of dynamic pile monitoring during initial driving and re-strike. Pile relaxation was observed during pile installation.At Towers F and G, setup effect was a key issue for the piles driven into the deep soft marine sediments. Drivability analyses were conducted to predict pile run, driving stresses, selection of hammer and refusal criteria. The piles were dynamically monitored during driving to estimate pile capacities. Due to the set-up effect in the Bay Mud, the piles gained up to 3.3 times the initial capacity during the re-strike and were in excess of the design capacity.This paper presents details of the design, construction, testing and performance of the driven pipe piles at temporary Towers D, F and G. Settlement data of the temporary tower foundations while in service confirmed the satisfactory performance of the pile foundations.INTRODUCTIONThe new east span of the San Francisco-Oakland Bay Bridge features a single tower self-anchored suspension (SAS) bridge, the largest of its kind in the world. The new east span replaces the existing double-deck steel bridge built in the mid-thirties. A span of the existing bridge had collapsed during the 1989 Loma Prieta earthquake but was repaired. Construction of the new east span commenced in 2008 and is expected to be completed for the Labour Day opening in 2013. Figure 1 shows a schematic (looking north) of the new bridge with its 160 m high main tower T1 in the middle, and Piers W2 and E2 at the west and east ends, respectively. The west and east spans of the SAS bridge are 180 m and 385 m, respectively.During construction of the SAS bridge, a temporary bridge, complete with towers and trusses, was used to support the box girders of the new permanent bridge until the loads from the box girders were transferred through suspension cables to the permanent bridge. The transfer of deck load from the temporary bridge to the main cable was completed in November 2012."

Jan 1, 2015

By P. Semberg, B. Bjorkman, C. Andersson

"In this study, the interaction between magnetite and the additive olivine was studied after oxidation as well as after isothermal reduction at temperatures in the 500º-1,300º C range. In the olivine sample, the forsteritic olivine particles react partly during the oxidation pretreatment to form magnesioferrite and vitreous silica along the particle corona. This breakdown of the olivine particles during oxidation liberates magnesium from the particles, which do not react until temperatures of above 1,150° C in reducing atmosphere. When the hematite in the sample is reduced, and when the temperature is high enough to allow solid-state diffusion at ~800º C, the magnesium of the magnesioferrite redistributes, so that the magnesium concentration approaches the same level throughout the iron oxide structure. For magnetite, this did not occur until 800° C. At 1,000° C, this magnesium reacts further with the silica in the glassy slag phase, which crystallizes into fayalitic olivine. At this temperature, the magnesium has diffused over distances of more than 600 µm from large olivine particles after 2 hrs reduction. From this point, the primary slag phase in the pellet, until melting, is solid fayalite. Upon reduction to metal, the metallization front concentrates the MgO in the remaining wustite, which can lead to MgO levels of up to 10 mole% locally. The melting point of the fayalite is raised from 1,145º C to a melting range of 1,238-1,264º C due to the MgO increase, as estimated based on phase diagrams, which were adapted to the pellets tested. Much of the olivine that remained unaltered in the oxidation process will be encapsulated by iron before the particles begin to dissolve in reducing conditions and, therefore, plays no role in the reduction before final melting of the particles occurs.IntroductionEnvironmental concerns have placed increasing pressure on the CO2-intensive iron and steel industries to further optimize operation toward higher productivity and more efficient use of reducing agents. At the same time, high demand for iron ore has caused new iron ores with lower grades and more complex chemistries to be taken into production. In Scandinavia, the main iron-bearing material is magnetite-based pellets with olivine, which allow operation with very low slag volumes and, hence, lower fuel rate ( Slagnes and Sundqvist Ökvist, 2008; Hallin et al., 1994). Both the MgO and SiO2 of the olivine, as well as the elements of the gangue of the ore, i.e., Si, Mg, Ca, Al and alkali, interact with the iron oxides to give the finished pellet product its final properties in the blast furnace. Tailoring the additive mix to be used for a certain iron ore for optimal product properties, therefore, requires detailed knowledge of the mechanisms by which these elements dissolve and react in the pellet."

Jan 1, 2015

By J. G. Groppo, A. E. Bland, B. K. Parekh, W. F. Stotts

Many coal preparation plants discard fine coal (generally minus 100 mesh) because it is difficult to beneficiate economically. At the Kentucky Energy Cabinet Laboratory (KECL), the waste streams from several Kentucky preparation plants were evaluated for cleaning with counter-current column flotation. A series of performance evaluations were conducted using a 0.05 m (2 in.) internal diameter (I.D.) 7.9 m (26 ft.) high laboratory column. The objectives of these tests were to assess the performance in terms of recovery and percent ash in clean coal and to optimize the operating parameters relative to combustible recovery and grade. Refuse streams containing 30-50 percent ash were upgraded to 2-8 percent ash with Btu recoveries of nearly 90 percent. A pilot scale column flotation cell was installed at the Bell County Coal preparation plant. This pilot plant utilized a 5.79 m (19 ft.) high and 0.15 m (6 in.) I.D. column to verify the performance data of the 0.05 m (2 in.) I.D. column for two different waste streams. Performance evaluation and pilot plant testing results related to scale-up are discussed.

Jan 1, 1988

By James J. Scott

Workshops were held in eight states during the period from December 12. 1975. through June 25, 1976, under U. S. Bureau of Mines Contract to the University of Missouri-Rolla. The workshops were designed to help define the Bureau's research and development priorities. At each workshop a summary of the current Bureau mine reclamation research was presented which was followed by identification of problems associated with mine land reclamation in the state where the meeting was being held. Discussions included the seriousness of problems locally and how the Bureau could best undertake research to assist the state in solving the problems identified. Participants included representatives of state agencies, educational institutions, and companies involved in surface mining. Attendance at these workshops totaled 201 persons who displayed a wide variety of opinions and ideas as to what should be done In government research and development efforts. A breakdown of these attendees is as follows: 91 state and Federal employees; 69 mine operators, equipment manufacturers and consultants; 33 educators and researchers; and 8 others representing such varied interests as environmental and conservation groups, news media and students .

Jan 1, 1976

By D. B. Stewart

In the past few years, much effort has been spent in elucidating the impact of diesel engines on the mine environment. This paper summarizes diesel fundamentals , exhaust emissions and typical tailpipe concentrations. Mine sampling results and an evaluation of exhaust treatment systems are discussed. A review of changes in pollutant concentrations between the tailpipe and the mine exit is made and suggestions are given to reduce operator exposure to diesel contaminants.

Jan 1, 1978

Jan 1, 1959

By N Clarke, J Hunt, A Barros, L Keeney

The Gramalote orebody is a large low-grade gold deposit situated in the San Roque municipality, 124 km north-east of Medellin in Antioquia, Colombia. It is jointly owned by AngloGold Ashanti (AGA) and B2Gold and is currently in Feasibility Study phase. In 2013 AGA requested CRCORE to undertake a preliminary study of the potential application at Gramalote of pre-concentration by screening, part of the Grade Engineering suite. 160 samples of coarse assay rejects (-3 mm) were tested and showed one of the strongest responses seen worldwide to that time, suggesting that about 70% of the gold could be recovered into 40% of the mass. This was seen as potentially markedly improving the Gramalote economics. A large-scale testing program was implemented on site to follow up these results. A total of 18 samples of 17 t each were mined along a pre-existing exploration adit. A complex test flowsheet allowed size fractions to be generated from the as-received material as well as after crushing to 53, 23 and 3 mm, all from the same head sample. The procedures were designed after carrying out a heterogeneity study to measure sampling errors. The coarser size fractions were designed to study the effect of crushing on upgrade response and predict the response on open-pit run-of-mine ore. The finer size fractions were designed to investigate means of predicting the upgrade response across the orebody. The large-scale testing closely confirmed the average upgrade response as predicted from drill core assay rejects but found that only the -53 mm crushed material accurately predicted the upgrade response of individual samples. Ore geochemistry was able to usefully distinguish samples with good and poor response. A small study on drill core suggested that, for Gramalote, fine crushed material distinguishes vein associated and disseminated values but not other factors that control actual outcomes.

Nov 10, 2020