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By Jacob Chacko

The east span of the San Francisco-Oakland Bay Bridge (SFOBB), which is one of the most heavily traveled bridges in the world, will be replaced due to seismic safety concerns. The majority of the new bridge will be founded on large-diameter (1.8 to 2.5 meters), approximately 60- to 100-meter-long pile foundations The large-diameter steel pipe piles and soil conditions are similar to those used/encountered in many offshore structures. Thus, the design methods used are based on site-specific modifications to the procedures recommended by the American Petroleum Institute rather than the conventional procedures that have been formulated and used for the design of much smaller piles. Pile foundations will experience their maximum loads during the design earthquake. For the Safety Evaluation Earthquake, tension loads of up to approximately 80 to 90 meganewtons (MN) and compression loads of up to approximately 120 to 140 MN were calculated. Due to the economic importance of the SFOBB and the consequences of catastrophic failure in both economic and human terms, the design and analysis of the pile foundations supporting the bridge consider a number of aspects of pile-soil behavior that are normally ignored. Those aspects include: 1) the effects of consolidation and setup, 2) the behavior under dynamic loading, 3) the losses of resistance under cyclic loading, and 4) the load-settlement behavior of the piles under severe cyclic loading conditions. Since the treatment of complex aspects of pile foundation behavior is not codified in any guiding documents, several project-specific methods were developed for design and analysis of the foundation piles.

Jan 1, 2002

By CHARLES L. WRIGHT

Coals may be divided into six classes-anthracite, semi anthracite, semibituminous, bituminous, subbituminous, and lignite. The first three cla~ can be distinguished by dHferences of composition, particularly the proportions of fixed carbon and the ratios of the fixed carbon to the volatile matter in the cools. The last three classes can be distinguished by di:fferences in physical character, chiefly in color and in manner of weathering. Lignite is brown, not black, and has generally a woody look, but it weathers in much the same way as subbituminous coals. On exposure to the air lignite slacks or crumbles. The lumps check and fall into small irregular pieces that exhibit a decided tendency to separate into extremely thin plates. Hence lignite deteriorates greatly during storage or long transportation. The most characteristic feature of the composition of lignite is a large percentage of moisture. '!his high moisture content reduces the fuel value of freshly mined lignite, and the partial evaporation of moisture, on expooure, causes th6 fuel to check and fall to pieces. Consequently, attempts to increase the efficiency of lignite as a fuel involve reducing its percentage of moisture and increasing its ability to endure storage and transportation. Both these results are accomplished by briquetting.

Jan 1, 1911

By F. K. McIntosh, L. A. Dahmers

"INTRODUCTION North Carolina has been the leading producer of mica in the United States, accounting for roughly 50 percent of the Nation's output. The producing area is a belt some 100 miles in width lying in the Mountain and Piedmont sections in the western part of the State. Ashe, Watauga, Avery, Mitchell, Yancey, Buncombe, Haywood, Jackson, Macon, Transylvania, Rutherford, Cleveland, and Lincoln Counties supply the bulk of production, while small amounts have been produced in Gaston, Catawba, Burke, Wilkes, Yadkin, Stokes, and Person Counties.To assist the operators and expedite the production of mica during the recent emergency, the Bureau of Mines drilled four of the more promising mica properties in this State. The results of this exploratory program are recorded in this report.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Division, L. B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, O. C. Ralston, chief, analyzes samples and makes beneficiation tests."

Apr 1, 1948

By N. Dixon

This report summarizes all work performed under U.S. Bureau of Mines Contract J0377014, "Development and Evaluation of Noise Control Techniques for Taconite Processing Equipment." Three areas of taconite processing equipment, grinding mills, fine screens, and crusher screens have been investigated. Extensive noise and vibration measurements have been made on grinding mills in which the process parameters that affect mill noise have been identified, and the level of shell impact noise around the mill defined. A multiplexing telemetry system was used to obtain shell vibration measurements from a rotating mill. Mill noise control methods were investigated and a partial mill barrier was built and tested on a semi-autogeneous mill. A noise reduction of approximately 3 to 6 dBA was achieved on the falling side of the mill. The use of rubber mill liners on autogenous mills has been evaluated. The noise sources on fine screens have been quantified, and noise control treatments developed. Noise reductions of 11 to 13 dBA were achieved at positions around the fine screen and some in-service testing has been done. Noise measurents of crusher screens were obtained and noise control through resilient screen decks appears to hold the most promise. Additional benefits might be lower life-cycle cost, since the service life of resilient decks is claimed to be longer than steel.

Jan 1, 1983

By Susan M. White

Increased coal production, wider use of indiscriminate mining techniques, improved cleaning methods, and greater emphasis on clean fuels is increasing the rate at which wastes accumulate Over the next several years, Colorado Plateau underground coal production is predicted to increase. Currently, mine refuse is deposited in canyons or lowland areas near mines. This study presents information on the nature of coal refuse and disposal practices on the Colorado Plateau. Samples were collected and analyzed to provide information to help formulate alternative methods for reclaiming refuse piles. The analyses were based on determining the capability of unmodified refuse to provide a suitable medium for plant growth. Local topsoils which would be used in reclamation were used as standards. Potential environmental hazards were assessed also. A general cost analysis was done for both surface and underground disposal and the advantages and disadvantages of each were assessed. Several problems were identified which, if solved, would increase the effectiveness of state regulatory programs.

Jan 1, 1982

By W. A. Parks

Stone that may be applied to purposes of construction is available in nearly all the inhabited parts of Canada, the most important exception being the prairie region, but, even here, the deficiency is overcome in many parts by a wealth of glacial field-stones. In many parts of the country, also, the accessible stone is of a quality so poor that brick is more generally used. There is a great difference, however, between stone that 'may be used' and stone suitable for buildings of a monumental type or even for 'trimmings' on the better class of dwelling in the cities and towns. It is in the latter sense that the expression 'building stone' is commonly used. Thus restricted the term includes varieties of sandstone, limestone, and granite, using the latter word in the custom of the quarryman, not only for the true granite of the geologist but for many other igneous rocks as well. Building stone of high quality grades imperceptibly into stone suitable for monuments, particularly in the case of the granites. The present review will deal with building and monumental stone in this restricted sense and will omit marble, although that material has been used to some extent for building. For instance, the Great West block in Winnipeg is built of marble from British Columbia.

Jan 1, 1925

By Martin van Staveren

In today's rapid changing construction world, the business pressures on piling and deep foundations reach sky-high levels. Ever increasing complexity of construction projects do severely contribute to these business pressures. Projects are often constructed in densely populated areas and located close to vulnerable buildings and infrastructure. The inherent uncertainty of ground conditions plays a dominating role in these foundation projects. Effective risk management is a key success factor for profitable and sustainable operations of piling and deep foundations. It starts with a fundamental requirement to be aware of risks. Next the different risk perspectives of all stakeholders in any foundation project have to be acknowledged. A simple and structured risk management approach is introduced, to demonstrate that effective risk management is not necessarily that complicated. A major element is the contractual allocation of risks, as a result from differing ground conditions. It is based on the so-called Geotechnical Baseline Report (GBR). The main objective of the GBR is to provide a clear contractual arrangement for the allocation of risks, arising from differing site conditions. The benefits of explicit risk management in general and contractual risk allocation in particular are illustrated with an example and experiences. The presented structured risk management approach, including contractual risk allocation, is still rather new. It proves to be promising for cost-effective risk control of piling and deep foundation projects, anywhere in the world.

Jan 1, 2006

By Ingemar Hermansson, Thomas Bjerendal, Mattias Grävare, Carl-John Grävare

"AbstractHigh strain dynamic pile tests (HSDPT) on driven piles have been carried out on a routine basis in Sweden for more than 30 years. The Swedish Commission on Pile research established, in the early 1980s, safety factors based on the percentage of piles tested. The safety factors could then be reduced, creating economic incentives for the contractor to carry out testing.Energy formulas adopted by our neighbour countries, Norway and Denmark, were not accepted in Sweden as a reliable method since the dynamic testing method was considered to be a more scientific and reliable method. It has become almost the only in-situ method used to verify geotechnical bearing capacity on driven piles.The typical Swedish geology of soft soils overlaying very hard strata makes it possible to verify high design loads, typically 20 kN per cm2 of pile cross sectional area for steel piles and 1,5 kN per cm2 for concrete piles.Conventionally a certain percentage of the piles have been tested in Sweden. The EC7, on the other hand states a number of piles to be tested, regardless of the total number of piles. The Swedish NA (National Annex) states a maximum distance between tested piles, which results in better distribution of the test piles over the foundation.For shaft-bearing piles in soft clays, dynamic pile tests have to be correlated by static load tests.Historical backgroundOn a research basis stress-wave measurements have been carried out for a long time in Sweden. One example is a project in the city of Gothenburg, conducted by Fellenius and Pejrud (1964). Strain gauges were glued on the reinforcement bars in 60 m long, precast concrete piles at 3 m and 25 m above the pile tip respectively. Evaluation was done with different methods such as dynamic formulas,stress-wave measurements and in addition compared with static load tests.In the 1975 Building Code in Sweden, driving criteria for concrete piles based on stress-wave theory were introduced, as summarized in Table 1. The driving criteria are intended for 3 and 4 tonne gravity hammers. For hydraulic rigs, which have free-falling hammers, the drop height indicated should be reduced to 80 % of the values in the table. The criteria were considered to include a safety factor of 3,0. For 330 - 450 kN pile load, pile with a standard a cross sectional area of 235 mm x 235 mm was used. For 600 kN load, the standard cross sectional area was 275 mm x 275 mm."

Jan 1, 2014

By R. S. McClain

The Federal Bureau of Mines investigated residues from aluminum plants, to determine if carbon could be removed by flotation while recovering fluorine and aluminum compounds for recycling to the reduction process. This publication summarizes studies on samples representing three types of plant waste products, supplied by three aluminum-producing companies. Samples of flue dust, pot skimmings, and pot linings from the various plants all responded to a simple turpentine flotation scheme to reject 90 to 97 percent of the carbon. Aluminum compound recoveries ranged from 42 to 94 percent on the flue dust, were about 95 percent on the pot skimmings, and ranged from 75 to 89 percent on the pot linings. Fluorine recoveries from the same samples ranged from 35 to 63, 92 to 95, and 77 to 86 percent, respectively. The pot linings contained soluble salts of aluminum and fluorine which were recovered by precipitation with sodium aluminate and carbon dioxide gas. Composites of residues from each plant responded to flotation much the same as the individual samples. Aluminum is produced by the electrolysis of alumina in a molten cryolite bath. The electrolytic reduction cell consists of a carbon-lined box containing a pad of molten aluminum which serves as a cathode, a carbon anode, and an electrolyte of molten cryolite in which the alumina is dissolved. Alumina is reduced to aluminum at the cathode, and carbon is oxidized at the anode.

Jan 1, 1961

By R. G. Burdick

The problems presented by old mine workings affect both present day mining and land development. An automated method of locating these old mines from the surface using electrical resistivity techniques was de-veloped earlier under a Bureau of Mines contract. Subsequent Bureau research has refined the techniques and expanded the area of study to a variety of geologic provinces. During this research, six mining areas in the United States were in-vestigated with the Bureau's automated resistivity method. This report describes the mining areas involved and the results of the resistivity investigations, which showed a high rate of success in detecting old mines. It also describes the field measurement techniques and data analysis procedures.

Jan 1, 1986

By J. E. Tobey

THERE are a lot of good things about this great industry of ours. Let us stop commiserating and consider some of the things that are right in this business. Coal is number one in the basic material industries. Our civilization owes more to it than to any other basic commodity. We are literally immersed in the benefactions of coal. In cur man-made world it is indispensable and we are constantly surrounded by objects, materials, and services which owe their existence to coal. Practically all the important materials, such as iron, steel, brick, cement, lime, rubber, glass, cotton, and wood have felt its magic touch.

Jan 1, 1939

By Lucius W. Mayer

WHILE the mind of the financier does not normally run along channels similar to those of his technical adviser, engineers, because of their exactness, are ever more called upon to manage affairs where financial matters are involved. It is, true, not a relatively large number have thus far functioned in this capacity. It is also true that the essentially financial mind could not serve in a responsible engineering position; for to be a successful engineer one requires precise thinking, making due allowance for factors of safety. To be a financier seems to require less aptitude for exact thinking than of enthusiasm and confidence in capitalizing prospective possibilities. Both require imagination, the engineer being, more conscious of the limitations of natural conditions. It is to be regretted that the engineer' stands so far aloof from financial matters. Many consider them- selves successful, as did Steinmetz, as long as their reward is the consciousness that they are giving supreme service to mankind. They are 'generally happy in their work and, like our honored brothers who are teachers, gain their greatest satisfaction, not in the amount of their remuneration so much as in the service rendered society and in the excellence of results achieved. Indeed, these sentiments bespeak character and command respect.

Jan 1, 1924

By Paul R. Terry

This paper presents a brief picture of the quality of coal produced in Eastern Canada for use in thermal generating stations. It describes, in particular, the characteristics of coals burned in six power plants -two in New Brunswick and four in Nova Scotia. Each station is dis-cussed in turn, and comments are made on the coals used therein with regards to origin and physical and chemical properties affecting station operation. A table of coal data shows, at a glance, the wide variation in the quality of coals received by these stations from producers in New Brunswick and Nova Scotia. "The promotion of improved coal quality for thermal generation can benefit our national economy." T HIS is the opening statement in a paper which was presented by Mr. D. A. Pirttinen at the Coal Division's Toronto meeting in April, 1960. In bringing the power engineer's viewpoint to the coal producers' attention, Mr. Pirttinen made a survey of utility steam plants operating in Canada, and the results of this survey formed the basis for his paper, which he titled: "Generating Station Coal Quality.

Jan 1, 1965

By Paul Worsey, Larry Frost, Braden Lusk, Seok Bin Lim

For certification of blast resistant windows, current tests consist of arena tests or large air gun tests. Arena tests involve the detonation of more than 1000 pounds of explosives with windows placed in the range of hundreds of feet. The result of an arena test is a loading on a window consistent with an expected industrial or terrorist blast. Due to the nature of this type of test, only a limited number of facilities are available and operational costs can be extremely high. Air gun tests involve the use of compressed air and a failing diaphragm fired through a large tube. Although this test is more cost effective and easier to administer with lower environmental impacts, it is not an explosive loading and does not create a negative phase on the tail of the pressure pulse. Simply using a small charge in close proximity to the window is not a viable option either. The pressure peak can be reached using this method, but the duration of the pressure pulse is such that the positive phase impulse is on the order of ten times less than that for an arena test.

Jan 1, 2006

By M. L. Bakker

Keywords: Pyrometallurgy, top submerged lance (TSL), nickel, PGM, calcium ferrite, lime ferrite The ISASMELT? top submerged lance (TSL) bath smelting process was developed in Mount Isa, Australia by Mount Isa Mines Limited (now a subsidiary of Xstrata plc) during the 1980s. By the end of 2011, the total installed capacity of the ISASMELT? technology will exceed 9 000 000 metric tons per year of feed materials in copper and lead smelters around the world. Commercial plants, operating in Belgium and Germany, are also batch converting copper materials in ISASMELT? furnaces. This TSL technology is equally effective for continuous converting processes, whereupon it is called ISACONVERT?. This paper presents the recently patented ISACONVERT? process for the continuous converting of nickel and Platinum Group Metal (PGM) containing mattes using the calcium ferrite slag system. The paper focuses on the potential application of the ISACONVERT? technology to existing nickel and PGM smelting complexes.

Jan 1, 2011

By Ilpo O. Auranen

Background: Mines of today are moving ever increasing tonnages of rock. The new ore bodies tend be of lower grade and located deeper in the earth?s crust. The industry?s focus to overcome this ?deeper but poorer? ore problem has traditionally been to lower the costs by increasing the scale of mining. This has resulted in an ever increasing size of mining equipment like drills, loading shovels, dump trucks. The main focus has been in reducing the cost per ton of mining. This cost focus has often resulted in increased waste rock dilution and more ore losses. From costs to value: Waste rock dilution means waste rock in the concentrator feed. It?s value in open pit mining is equal to the value of ore it replaces. In underground mining, waste rock dilution?s value is equal to the value of ore it replaces added to the costs of mining it. It is commonly accepted that waste rock dilution in open pit mining ranges between 5 and 20% and in underground mining between 5 and 40 % . In a typical large open pit mine ore value is from 20 to 60 USD per ton and mining costs are 1 to 3 USD per ton. One percentage point reduction in waste rock dilution represents savings corresponding to about 20% of total mining operation costs. The difficulty of reducing waste rock dilution comes from the complicated nature of the ores. Accurate ore waste-border detection has not been possible due to excessive costs. Core drilling combined with geochemical lab analysis is the most accurate method for locating ore waste borders. However, it is also expensive and time consuming, which is why it is often combined with somewhat lower cost methods like sampling drill cuttings from blasting drill holes or from reverse circulation drills and analyzing them in a laboratory. The main drawback with these methods, in addition high costs, lies in the sampling accuracy and in the quality control of the whole process when a large number of samples have to be handled manually. In every mine it is possible to halve waste rock dilution by using new on-line analysis technology .

Oct 1, 2009

By Fred Delabbio

There are presently several issues that the mining industry is facing, such as underground air quality, deep mining and green house gas emissions, which could be addressed by the application of alternate energies. Several aspects must be considered by the industry in any drive to introduce new technologies within the context of a producing underground mine. This article presents several operational and support aspects that will evaluate the relevance of alternate energies, with emphasis on hydrogen power systems: operational drivers, commercial supply of technology, site supply system requirements, health and safety, capital and operating costs, mine production, corporate philosophy, and role of government. It is concluded that introduction of alternate energy technology requires a step-wise progression: Applicability to the industry, proof of concept testing, development of generic infrastructure, power systems and regulations, whole system studies and detailed studies of cost and risk versus benefits. The current initiative to apply fuel cells is at the proof of concept stage, entering the generic infrastructure stage.

May 1, 2007

Tracer gases are an effective method for assessment of mine ventilation systems, but their dispersion characteristics can differ substantially as ventilation parameters, such as flow path and velocity, vary. This research utilizes Computational Fluid Dynamics (CFD) to model a simplified full scale model mine, details a sensitivity study examining mesh size for an underground coal mine simulation, and examines gas dispersion parameters to determine the optimal model methods for simulation of tracer gases in underground coal mines. These models can be used to determine how a given tracer gas profile might be generated in a mine or areas of a mine that are not accessible, for example, immediately following a mine disaster. Accurate simulation scenarios can allow for the remote determination of the status of the ventilation network, but the sensitivity of the simulation at mine scale must be carefully examined.

Jan 1, 2012

Judicious placement of a range of geotechnical instruments was employed at the Tasmania gold mine, Beaconsfield, Tasmania, as a key strategy in the monitoring of rock mass conditions over the past four years. The range of instruments employed included vibrating wire stress-meters and hollow inclusion cells to monitor changing stress conditions, resistance wire and multipoint borehole extensometers to monitor the impact of stress changes on the integrity of the rock mass, and instrumented cable bolts and threadbar bolts to monitor the static and dynamic impact of rock mass changes on the installed ground control system. Initially the monitoring was of a qualitative nature, monitoring change from the time of installation. The value of the output was considerable when considered in relation to the ongoing seismic record which was also being monitored. It was clear from the seismic record and the monitoring results that stope blasting was the primary trigger for changing rock mass conditions. However, it was unclear how well observed behaviour was reflecting conditions anticipated by elastic numerical modelling. The latter had predicted significant stress increase in the near field of man-access footwall development. Qualitative monitoring and visual inspection did not support the modelling prediction, and this led to a program of quantitative measurement being undertaken. Measurement of the absolute stress condition in the backs of footwall development immediately adjacent to monitoring hollow inclusion cells provided the benchmark for tracking quantitative stress change. The program provided insight into the evolution of principal stress field magnitude and orientation in relation to rock mass change observed with extensometers and instrumented ground control elements, as well as providing a degree of calibration between the elastic numerical modelling and the virgin stress field. Calibrated monitoring data has also provided a useful benchmark for finite element modelling which is to be used for future mine-wide design.

Nov 25, 2010

By David Norval

Ni, Co, Cu and Pt, mattes are common materials that require granulating and milling of the resultant granules for further processing. This route is acceptable if the material is brittle (friable) which is a property associated with the higher sulphur mattes. For lower sulphur levels, where the matte is less amenable to milling, the costs of the milling increases. This paper will compare water granulation with certain dry granulation processes and the downstream processes required for Hydrometallurgy. It will further introduce and expand on atomisation which offers a further safety benefit in the control of the metal flow into the 'wet zone' with the use of a tundish flow control also reducing the conversion from the matte to powder in one fairly straightforward operation.

Jan 1, 2006