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By Philip Bonanno

The first major project in Boston's new access to Logan Airport was an Immersed Tube Tunnel which extended 3,600 ft. from South Boston to East Boston across Boston Harbor. Twelve tube sections, 300 ft. long x 80 ft. wide x 40 ft. high, were lowered into an excavated trench which was then backfilled. The depth of the trench at mid-channel was approximately 100 ft. below mean high tide. At the East Boston end the tube terminated close to the present shoreline. At the South Boston end the tube terminated approximately 600 ft. inland from the shore line where a ventilation building was required. The depth to subgrade from existing ground at the ventilation structure was approximately 85 ft. The soil profile at this location consisted of 50 ft. of miscellaneous rubble fill, 25 ft. of Boston blue clay, and 10 ft. of glacial till. A small amount of weathered argellite existed at the north end of the structure. Part of the Morrison Knudsen, Interbeton, J.F. White, Joint Venture contract to construct the Immersed Tube Tunnel (ITT) was the construction of a cofferdam at the tube/ventilation building interface. The ventilation building was to be built as part of another contract. The construction of the cofferdam and the excavation to the building subgrade was the responsibility of J.F. White Contracting Company.

Jan 1, 1994

By K. Y. Haramy

Coal mine bumps involve the violent, rapid failure of coal and rock around a mine excavation. Deep coal mines with strong roof and floor rocks and high-stress conditions frequently experience face and rib bumps. The bump problem is becoming more severe as mining depth increases, prompting efforts to control high stress in advance of mining. This Bureau of Mines report presents a review of the most widely used methods to detect and destress high-stress zones along coal faces and an investigation of stress-related bump problems and destressing techniques at a cooperating mine. Geotechnical instrumentation and microseismic methods were used to better understand bump occurrences in underground coal mines. Laboratory tests of the drilling-yield method for high-stress detection were conducted to determine the correlation between the volume of cuttings obtained and the magnitude of the applied stress at various confining pressures. A three-dimensional, multiple-seam computer modeling program, MULSIM, was used to evaluate the effectiveness of stress-relief methods. Modeling results indicate that dangerously high-stress areas can be controlled by either proper planning or destressing. Proper mine planning guidelines and destressing methods such as volley firing, hydraulic fracturing, and auger drilling are discussed.

Jan 1, 1988

By H. Ranjbar

The Darrehzar porphyry Cu deposit is situated in the Urumieh-Dokhtar magmatic suite of Central Iran. The REE and trace element data suggest that the deposit lies within a continental margin setting. Phyllic and propylitic alteration are pervasive in the area but potassic and argillicalteration are not readily recognized on the surface. This is possibly the result of super gene weathering of the surface rocks or because of an intense phyllic overprint. Poor soil development and abundant outcrop make the area suitable for a case study of lithogeochemical exploration technique for Cu deposits. A total of 262 rock samples was collected over the area and analyzed for 15 elements. The geochemical data cor-relate with the mineralogical composition of the rocks with the phyllic zone being marked by high-er concentrations of Si, Al, K, and by a high sericitization index while Ca, Mg, Sr, total Fe and Mn are more abundant in the propylitic zone. The lithogeochemical study indicates a metal zonation from a Cu + Mo-rich core to a Zn + Pb ± Ag-rich outer zone. Principal component analysis is useful for separating element associations, which in turn reflect the alteration halos. Principal components 1 and 2 depict alteration zoning, where-as 3 shows an association of Cu and Mo, that roughly defines the mineralized area.

Jan 1, 1997

By Robert M. Weidenhammer

For years before the war, Coal had the reputation of being a sick industry. Currently it is operating at peak production and succeeding pretty well in keeping out of the red. But, says Mr. Weidenhammer, it will have a relapse as soon as the war ends unless (1) working capital can be built up; (2) it gets the support of the people and Congress; and (3) a truly long-range national fuel policy is formulated.

Jan 1, 1943

By AIME AIME

TRANSFER to the Bureau of Mines of the responsibility for conservation and production of helium, and announcement that a proposal has been made to the President for commercial operation of the Los Angeles has attracted new attention to the helium program of the Government. The matter is one in which mining engineers, and the mining industry in general, have a peculiar interest. Helium is a byproduct of the petroleum and natural gas industry. It is found in certain of the natural gases which have themselves been discovered, in the main, in the search for oil. If it is to be produced on a large scale, the conservation and development of the fields will necessarily be done by the men of the oil and gas industry. There is no known or expected source of supply of quantities of commercial importance save in the natural gas fields. Not all gas wells supply helium and none of them supply it in important percentages. If it were necessary to prospect a field, develop it, lay pipe lines and build production plants for the helium alone, the cost would be prohibitive. On that basis helium would necessarily be restricted to essential war uses, where cost is subordinate to need. As a byproduct of the natural gas in certain, at least, of the fields in the United States there is distinct reason for anticipating that it may be produced in amounts and at a cost that will permit its regular use in commercial airships.

Jan 1, 1925

By Michael I. Brittan, Craig M. Sams

"Economies of scale and the variable characteristics of many large ore deposits have resulted in grinding installations using very large SAG mills fitted with variable speed drives. Low-aspectratio single-stage SAG mills were introduced in South Africa to process the consistent gold bearing Witwatersrand quartzites. Elsewhere, circuits were patterned after the more conventional North American circuits with high-aspect-ratio SAG mills followed by ball mills. This paper provides information on two recent Gold Fields group installations covering both types of SAG mill in large, single-stage applications. While these operations process similar tonnages, the mills represent opposite ends of the aspect-ratio spectrum. The Tarkwa mine in Ghana employs a low-aspect 27’ x 42’ 14MW SAG mill. The St Ives mine in Australia operates a conventional 36’ x 18’ 13.4MW SAG mill.INTRODUCTIONGold Fields is one of the world’s largest gold producers with annual production of approximately 4.2 million ounces. The Gold Fields group has operations in South Africa, Ghana and Australia, along with numerous exploration sites and advanced projects in several other countries. This paper discusses new milling operations in Ghana and Australia.TarkwaThe Tarkwa Gold Mine is located in Ghana, West Africa, approximately 350 kilometers west of the capital city of Accra (Figures 1 and 2). The site conditions are tropical with an average annual rainfall of 1,930 mm and a maximum temperature of around 35°C."

Jan 1, 2006

By Jason N. Scott

CFA piling is a ?blind? construction process that relies heavily on the rig instrumentation to produce sound piles. If the data measured and recorded during construction can be made available to engineers and managers within hours after construction then there are many economic and quality control benefits that can be realised. A state of the art CFA instrumentation and data management process has been developed in the UK. The key components of the instrumentation, GSM data service and the central database are described. Many benefits to the business have been realised and, where possible, these are quantified.

Jan 1, 2006

By Francis Gray

Mr. F. W. Gray: It is not my intention to read my paper as it is too long, so I will touch only on the high lights. The Sydney field is the most favourable example of undersea coal mining that exists, and I have not been able to find anything like it elsewhere. The nearest approach to it is a field in England where the Whitehaven collieries are operating, but it has a lot of faults. The net result of these faults so far met with in the seaward advance of the workings has been to increase, by something over 100 feet, the gain in depth of cover, in a distance of approximately three and three-quarter miles. In the Sydney field there are no faults of any consequence. On the east side, the English measures rise. In Australia the sea bottom fell and the cover became too light. On Vancouver Island the coal ran out, and in Japan the seams are steep and contorted. The Chilian fields resemble our own to some extent. An inundation of two collieries took place there some time ago, due, it is said, to the rise workings being allowed to approach the sea bottom too closely in the vicinity of a fault. The Cape Breton undersea field has been proved over a frontage of about thirty miles and has been attacked and penetrated for a considerable distance along that front. We have passed the prospecting stage and now generally use developed land areas as points of attack to win the undersea coal. Of our mining under the sea, it can be said that, with the exception of No. 1-B and Princess colliery, Sydney Mines, no real attempt has been made to win the undersea coal.

Jan 1, 1927

By Wade Edward Speer

The Hiddenite District of Alexander County, NC has produced some of the world?s finest large emeralds since the first one was discovered 134 years ago. In fact, North America?s largest emeralds come from the district, making this one of the continent?s most unique gem deposits. In addition to emeralds, the Hiddenite District is also famous as the discovery site for the rare spodumene mineral hiddenite, first identified in 1881. Nowhere else in the world do these two minerals naturally occur together. The emeralds are a unique color variety of beryl (Al2Be3Si6O18) with trace amounts of Cr+3 and V+3 substituting for Al+3. The hiddenite (LiAlSi2O6) crystals also exhibit emerald green color due to traces of chromium. Consisting of three large deposits and numerous prospects, the district encompasses an area of 10 km2 (4 sq miles) centered on the small town of Hiddenite. Operations at the Adams, Ellis and North American Emerald Mines properties have been productive at irregular intervals since the 1880s. Currently, only the North American Emerald Mines property is being mined on a regular basis. Recent activity there has exposed a 3-hm2 (7.4-acre) pit with depths of 25 m (82 ft) that provides the best exposures of unweathered bedrock seen in the district in more than 120 years. Although no official records exist, public and private data indicate that the production of the entire Hiddenite District from 1880 to 2007 is about 70,000 carats of emerald and 20,000 carats of hiddenite. The bulk of the emeralds came from the North American Emerald Mine property (NAEM, formerly known as the Rist Mine) where sustained mining replaced the previous sporadic prospecting in 2000.

Jan 1, 2009

By Theodore L. Turner

This Bureau of Mines report describes calcination of kaolinitic clay in a direct-fired 2-1/2- by 24-ft rotary kiln at 750° and 775° C. Methods for preparing kaolin feed materials and characterization of calcined products are discussed. Approximately 99 pct of the alumina in a typical eastern Georgia kaolin was soluble in HC1 after calcination at either 750° or 775° C.

Jan 1, 1982

By L. F. Miao

Studies were carried out to investigate the ultimate soil pressure acting on pile(s) undergoing lateral soil movement in soft clay. A special apparatus has been designed to apply a uniform rectangular profile of lateral soil movement on the rigid pile(s) with pinned head and tip conditions to obtain the ultimate soil pressure. The piles were 16 mm (5/8 in) in diameter. For the pile group tests, the behavior of different number of piles (2, 3, 4, 6 and 9), pile arrangements and center-to-center spacings (3 and 6 diameters) were investigated. In this paper, the group factors of 11 combinations of number of piles, pile arrangements and pile spacings are presented. The group factors are given for individual piles in a pile group as well as for the entire group. Generally, the group factors of individual piles in a group varied significantly according to pile spacing in both directions, and pile arrangement; the group factor of the whole group reduced with an increasing number of piles, and increased with increasing pile spacing. For a pile group with the same number of piles but different pile arrangement, no significant difference was found in the group factors for the entire group.

Jan 1, 2008

By S. Weiss, E. Espinoza

The El Sauzal gold-silver deposit is a high-sulfidation, epithermal precious-metals deposit hosted by an east-dipping sequence of dacitic and rhyolitic pyroclastic and debris-flow units of probable Oligocene age. Total gold production since startup in late 2004 is approximately 450,000 oz. of gold. Above the sulfide boundary gold is mainly disseminated as small grains interstitial to alunite, kaolinite and quartz. The majority of the ore is found in quartz-alunite-kaolinite altered rock that mantles tabular to irregular silicic cores of vuggy, residual quartz ±kaolinite ±dickite. Grade domains are modelled as subhorizontal to east and southeast-dipping. Higher-grade domains cut across alteration zones and also coincide with transitions from vuggy quartz to quartz-alunite-kaolinite. The highest grades are commonly found marginal to vuggy quartz in transitional, hematite-rich quartz-kaolinite and quartz-alunite-kaolinite rock.

Jan 1, 2007

By L. G. Marshall

This report describes dredging and processing of sand and gravel from a glacial-fluvial deposit in the Raccoon River valley near West Des Moines, Iowa. Preliminary cleaning and separation of the sand and gravel at the dredge site with subsequent transportation to separate plants and the production and disposal of the various grades of aggregate material are also described. The geology of the deposit is summarized. A tabulated summary of costs in units of labor, power, and supplies is included.

Jan 1, 1963

By Luiz Filipe Cardoso de Oliveira, Alex Milton Albergaria Campos, Paulo Santos Assis

Em usinas siderúrgicas integradas a coque, o carvão mineral tem papel fundamental principalmente na produção de coque metalúrgico, que será utilizado nos altos-fornos para produção do ferro-gusa. O coque é produzido a partir de misturas, de carvões minerais com diferentes propriedades, formuladas para atender os requisitos operacionais do processo de coqueificação e a garantir a qualidade do ferro-gusa que será produzido nos altos-fornos. Além disso, está mistura deve ter o menor custo possível uma vez que a maior parte do carvão metalúrgico utilizado no Brasil é importado, representando assim uma grande parcela do custo do aço. O grande desafio do setor é obter misturas de carvões que atendam a coqueria e produzam coque com alta qualidade e baixo custo. Para tanto, é necessário uma otimização de vários processos, desde a compra e transporte do carvão até sua estocagem, formação das misturas e abastecimento da coqueria. Com isto, este trabalho vem com o objetivo de sugerir uma otimização e planejamento da mistura de carvão para a coqueria com a utilização de rejeitos plásticos de menor valor agregado na mistura que possibilitem a produção de coque com menor custo e com a qualidade exigida no processo de fabricação de aço.

Oct 1, 2019

By M. Sharafodin, A. A. Hassanipak

Abstract - The essential aims of additional borehole drilling are to improve the reliability of grade and tonnage estimates in each reserve class and to increase ore tonnages. The "GET" function presented in this paper considers strategies for achieving both of these goals simultaneously, and therefore is advantageous for selecting sites for additional boreholes. The "GET" function is either a linear or a non-linear product of three variables G, E, and T: f(G,E,T,) = G??E??T??where the values of any or all of the exponents ?, ?, and ??may differ from unity at the discretion of the user. G and E are the average estimated block grade and the average estimation error for ore blocks in one vertical column, and T is the compounded ore thickness within the column. To illustrate its utility, the GET function has been used for determination of the most advantageous sites for additional drilling in the Shah-Kuh Pb-Zn deposit in west central Iran.

Jan 1, 2004

By Kim M. Cornelius

Musculoskeletal injury is a term used to describe a wide range of soft tissue disorders which affect the nerves, tendons, and muscles. Common examples include lower back pain, tendonitis, and carpal tunnel syndrome. The majority of these injuries are not the result of sudden mishaps, but usually develop gradually from repeated wear and tear. Symptoms may first appear after weeks, months, or even years. Symptoms may result from many types of activities, performed at work or at home, and it is often difficult to attribute a single event. In fact, it is more common to identify the factors which may have contributed to the development of the condition. The terms repetitive strain injuries or cumulative trauma disorders (CTDs) have been commonly used to refer to disorders that have occurred due to work related activities (Putz-Anderson, 1988; Fraser, 1989). Three main risk factors contribute to CTDs: force, repetition, and awkward postures. Any one or combination of these may contribute to the development of CTDs. Therefore, the design of equipment in conjunction with the required tasks should attempt to reduce these risk factors. Examining the layout of the work area to help identify tasks which may contribute to cumulative trauma is necessary. The following list(Putz-Anderson, 1988), describes ergonomic concerns that, overall, should be minimized at the work area:

Jan 1, 1997

By C. H. Herty

As the problem of inclusions in steel has become increasingly important, more and more attention has been paid to the source of the oxide inclusions in steel. In killed steels the oxide inclusions are traceable to the reaction of deoxidizers with the iron oxide dissolved in the steel during the refining period of the open-hearth heat. In a large class of steel known as "rimming steel" the action of the steel during solidification depends entirely on the gas evolved, and this evolution in turn is controlled by the amount of iron oxide in the liquid steel in the mold. It is therefore of great importance to be able to determine the amount of iron oxide dissolved in steel and to devise methods for the control of iron oxide in any class of steel. The object of the present investigation was to obtain a true value of the oxygen content of liquid steel. If the steel has not been deoxidized, the greater percentage of the oxygen is present as iron oxide in solution.

Jan 1, 1932

By S. Thorley

In engineering design of operator?s compartments, in underground mining equipment, ergonomics principles are often neglected or not given the full recognition they deserve. This paper defines ergonomics, applies it to machinery in an underground mining environment and describes the ergonomics analysis undertaken during the design phase of an EJC extra-low-profile mining loader. Encompassing the design of the operator?s compartment of this new loader, this paper illustrates the importance of ergonomics principles within the collective design process, ensuring that it is fully integrated into the design approach. An ultimate aim of this study is to ensure that all future designs follow this route to guarantee not only the outcome of a highly efficient, cost-effective and productive machine but that it is also takes the human factor into account, not only in maintenance but also in operation. Maximizing comfort will have the ultimate outcome of actually increasing productivity.

Jan 1, 2006

The negative effects of pyrite and pyrrhotite on thiosulfate gold leaching have been investigated. Possible remedies to reduce some problems are discussed. In a gold bearing pure silicate ore, 92% of gold could be extracted within 3 hours using a solution containing 0.2 mol/L ammonium thiosulfate, 0.9 mol/L ammonia, 30 - 300 ppm copper sulfate and 8.6 ppm dissolved oxygen at pH 10.26. The thiosulfate consumption was 7.1 kg/t under these conditions and could be further reduced to 3.5 kg/t by decreasing the dissolved oxygen to 0.3 ppm. Addition of 16% pyrrhotite or pyrite into the silicate slurry led to a decrease in gold extraction by 2% or 9% respectively and an increase of thiosulfate consumption by 11 kg/t or12.8 kg/t respectively in three hours. Several adjustments, such as increasing copper ion and ammonia concentration and reducing the dissolved oxygen level to 0.3 ppm resulted in increased gold extraction and lower thiosulfate consumption despite the presence of these sulfides.

Jan 1, 2005

By Wils L. Cooley

Although electric utility companies have been active in grounding and bonding within substations, the mining engineer or mine electrical engineer is not involved to the extent that he can be fully up-to-date on the most effective practices for substation construction. The coal mine power system is grounded in a fundamentally different way from most other industrial power systems and is subject to considerable Federal and State regulation. At this time, there is little information that is directly applicable to the mine situation, especially if the substation must be built in an area of limited size or in low-conductivity earth. The objective of this guide is to provide specific engineering information to the mining; industry. Using as little theory as possible, it was written to be general enough to cover most substations, but specific enough to provide direct help with each substation. It will attempt to recommend practice that is in agreement with present Federal rules and regulations.

Jan 1, 1980