Search Documents

By V. Castranova

"A pneumoconiosis is best defined as the accumulation of dust in the lungs and the tissue's reaction to iu presence. Thus, silicosis is the name given to the fibrotic disease of the lungs caused by inhalation of dust containing silicon dioxide, primarily in the free crystalline form. Coal workers' pneumoconiosis (CWP), which was originally thought to be a variant of silicosis, results from inhalation of coal mine dust that usually contains relatively small amounts of free crystalline silica.HISTORYSilicosis is the older and more well known of these mineral pneumoconiosis. In contrast, CWP was not recognized as different from silicosis until the pivotal work of Collis and Gilchrist. 26 They noted that coal trimmers, i.e., special stevedores who leveled coal in the holds of ships at the Cardiff and Swansea docks in Wales, developed identical nodules on the chest radiograph to those of underground miners. The difference was that these men had never worked underground and that the coal was washed before it was loaded into ships; thus, it was unlikely that these men were exposed to silica. Gough54 examined the lungs of coal trimmers who died and found that the histologic appearance of the pulmonary lesions was distinctly different from the whorled nodules seen in silicosis. Gough,"" and subsequently Heppleston,"" then showed that the lung lesions in coal trimmers were similar to those in underground coal miners and different from those of classical silicosis. Nagelschmidt 78 analyzed the mineral content of miners' lungs that became available at autopsy. These studies caused him to propose a scheme in which the relative proportions of silica, other minerals, and/or coal deposited in the lungs determined the type of pulmonary response which develops, i.e., classical silicosis, mixed-dust disease, or CWP."

Nov 1, 1995

By Bruce F. Grant

"INTRODUCTION The future of oil production in the part of the Appalachian region included in southwestern Pennsylvania; West Virginia, and southeastern Ohio is directly dependent on the maintenance of existing wells. This report presents an analytical study of the methods used in oil-well reconditioning in this area. The study is part of a research program designed to evaluate those means of stimulating oil production that can effectively and economically maintain present oil-production rates and make it possible to keep existing wells in operation. Well-reconditioning work was curtailed during the war; therefore, an abnormally large number of wells in the Appalachian Region is now in need of repair. Because the lubricant content of Appalachian crude: oils is high and the refined lubricating oils an; particularly suited to use in high speed, high-temperature engines, the demand for these crude oils during the war exceeds, the maximum rate of production obtainable under wartime operating conditions. Increases in operating, expenses, inability to meet war-time reconditioning costs, and inflexible price structures caused the abandonment of an alarming number of wells during the past 4 or 5 years.As a means of increasing regional oil-production rates, new drilling in the older fields for primary production generally is uneconomical because reservoir pressures in most of the fields have virtually been depleted and the production rates of newly drilled wells are small."

Feb 1, 1948

By Leon Maday, Dan L. Pecha, Jeremy Johnson, Daniel N. Adams

The Brightwater conveyance system includes 26 km of tunnels, a 130 mgd pump station, 2 km of micro tunnels, and a 2.4 km outfall. The tunnels extend from Woodinville to Puget Sound through varying soils in 1 to 7 bars of hydrostatic pressure and depths to 185 m. The tunnel diameters range from 4 to 6 m and include numerous lining systems. This paper highlights major shaft and tunnel design, including dual cellshafts, multiple pipe configuration tunnels, polymer concrete segments, and the use of a one pass lining designed to convey high pressure effluent.

Jan 1, 2005

By Shahriar Vandani, Andy Herlache, Andrew Bro, Wei-Yu Chen

"The Presidio Parkway Project will reconstruct approximately 1.6 miles (2.6 km) of highway, including seven new bridges, three new cut-and-cover tunnels, and a new undercrossing connecting the Golden Gate Bridge to the City of San Francisco, California. The project site is approximately 5.6 miles (9 km) from the San Andreas Fault, capable of producing magnitude 8 earthquakes. Seismic hazards include strong ground shaking, soil liquefaction, ground settlement, and lateral spreading. The Main Post Tunnels (MPT) are two parallel cut-and-cover concrete tunnels approximately 1100 feet (335 m) long. The MPT site underlain by loose sandy soils susceptible to liquefaction and lateral spreading. Excessive racking and permanent displacement due to lateral spreading are identified as the main seismic vulnerabilities. Analyses showed that without ground improvement, tunnel racking of over 5 inches (13 cm) and permanent lateral tunnel displacement of up to 15 feet (4.6 m) could be anticipated. Cement Deep Soil Mixing (CDSM) is proposed to mitigate slope displacements and increase lateral stiffness of the foundation materials to reduce tunnel racking. A series of 2-D fully dynamic time domain analyses were performed to evaluate the performance of CDSM, confirm that performance criteria are met, and optimize the CDSM geometry and replacement ratio. The use of CDSM reduced the permanent tunnel displacement from over 15 feet (4.6 m) to less than 1 inch (2.5 cm). Tunnel racking was also reduced significantly. The adopted analytical approach presented herein can be considered for future tunnel design projects in seismically active areas.Introduction The Main Post Tunnels (MPT) are an integral component of the Presidio Parkway project which will replace the existing facility with a new multi-lane roadway between the Golden Gate Bridge and the City of San Francisco. The MPT are two parallel cut-and-cover concrete tunnels approximately 1100 feet (335 m) in length. As shown on Figure 1, the project site is located in a seismically active area, about 5.6 miles (9 km) east of the San Andreas Fault and 12.5 miles (20 km) west of the Hayward Fault. The San Andreas Fault can generate magnitude 8 earthquakes while the Hayward Fault is capable of producing magnitude 7.3 earthquakes. The design Peak Bedrock Acceleration (PBA) is 0.46g for the upper level design earthquake. The project alignment is shown on Figure 2."

Jan 1, 2014

By Hengwei Yan, Zhanwei Liu, Wenhui Ma, Ping Xiong

The sulfur in high-sulfur bauxite not only pollutes the environment but also harms alumina production. This study investigated the removal of sulfur from high-sulfur bauxite by adding Zn or ZnO during the Bayer process. The results showed that the different valence sulfur (S2−, S2O3 2−, SO3 2−, and SO4 2−) in sodium aluminate solution can be effectively removed by adding Zn during the digestion process. Adding ZnO removes the S2− in liquor, but the other sulfur compounds (S2O3 2−, SO3 2−, and SO4 2−) are not affected. The mechanism of sulfur removal has been elucidated, where the S2O3 2−, SO3 2−, and SO4 2− are first reduced to S2−, and after adding Zn, the S2− enters into red mud in the form of ZnS. The ZnO then reacts with S2− to generate the ZnS that enters into red mud. Thus, this is a new and effective method of sulfur removal by adding Zn during the digestion process. The results shed light on the removal of sulfur from high-sulfur bauxite during alumina production.

Jun 24, 2020

By D. Ksinsik, R. Boisvert, D. Leblanc

Casting, cooling and crushing/sieving of ferroalloys has followed a well-established pattern in the whole ferroalloys industry for many years. Usually liquid metal or alloys are cast into flat open moulds of various shapes and forms, and after solidification the product is removed from such mould to further cool down to a temperature where subsequent handling steps are feasible. Common to all mechanical product fractioning is the generation of dust and fine size material with lower product value. For almost 10 years, Bécancour Silicon has investigated alternative roads to improve technology and/or reduce or solve problems related to those disadvantages. Since 1995 Bécancour Silicon operates a special silicon granulation plant targeted to product for the chemical treatment/conversion of silicon for silicones production. Prior to the development of the granulation process, various systems had been evaluated, among others the vibrating casting bed, now in operation elsewhere but judged inappropriate because of the tapping volumes to be handled at Bécancour Silicon and other disadvantages. After evaluation of all aspects of heat transfer, radiation, and conductivity in relation to transfer media and within the product, a novel system was designed and built.

Jan 1, 2004

By Richard E. Thill

The Bureau of Mines' Oil Shale Data Bank (OSDB) was created in 1976 to serve as a centralized source for the storage, retrieval, and dissemination of technical literature, patents, and information on research projects in oil shale. Thousands of bibliographic references, patents, and research projects relating to the mining of oil shale have been identified, abstracted, and indexed according to selected keyword topics. The resulting data bank listings are contained in three sections, each with a separate keyword breakdown for use in rapidly identifying references pertaining to a specific subject. All references cited in the OSDB were published prior to an established cut-off date of May 1, 1981, when a redirection of Bureau of Mines programs resulted in the loss of project funds and the subsequent phasing-out of data bank operations. ACKNOWLEDGMENTS The oil shale data bank listings are the result of a team effort of the project staff. The contributions of Jimaleen Jansma for keypunching, information acquisition, and data entry, and John Brandenburg and Sandra rake for keywording and information acquisition are gratefully acknowledged. Appreciation is expressed to the staff members of the Smithsonian Science Information Exchange, Washington D.C. for their cooperation in supplying data on recent research projects in oil shale for inclusion in the OSDR listings. Appreciation is extended also to the staff of the Gallegos Research Group for assisting with computer services to obtain the final printouts and transfer of files onto magnetic tape.

Jan 1, 1982

By R. A. Puchner

The location of a decline shaft portal can have far reaching implications if the geotechnical conditions are not suited for safe and cost effective excavation. Ideally the portal should be positioned in an area where the excavation requires minimal support and the portal can be formed in reasonably competent rock. In many cases, however, the shaft is linked to an underground mining plan and the shaft may have to pass through poor ground conditions. Determining the optimal position at which tunnelling can commence i.e. the portal, is critical and requires a thorough geotechnical investigation. Methods used to acquire information for the assessment of the ground conditions are discussed in this paper. Selection of the appropriate methods is dependent on the anticipated ground conditions, the phase of investigation and restrictions due to site access and budget. Non-invasive techniques are often used during preliminary phases and invasive techniques for the detailed investigation. The methods used during each phase of investigation are discussed. Two case studies are then presented to provide examples of the investigative methods used in two different environments. The first being a flat featureless site with thick soils and deeply weathered bedrock, while the second is a mountainous site with differentially weathered rocky outcrops. Based on these cases, it is clear that an understanding of the geology and geomorphology of the site is vital to the final geotechnical assessment. Key words: Decline shaft, boxcut, geology, geomorphology, geotechnical, portal.

Jan 1, 2009

By R. A. Puchner

The location of a decline shaft portal can have far reaching implications if the geotechnical conditions are not suited for safe and cost effective excavation. Ideally the portal should be positioned in an area where the excavation requires minimal support and the portal can be formed in reasonably competent rock. In many cases, however, the shaft is linked to an underground mining plan and the shaft may have to pass through poor ground conditions. Determining the optimal position at which tunnelling can commence i.e. the portal, is critical and requires a thorough geotechnical investigation. Methods used to acquire information for the assessment of the ground conditions are discussed in this paper. Selection of the appropriate methods is dependent on the anticipated ground conditions, the phase of investigation and restrictions due to site access and budget. Non-invasive techniques are often used during preliminary phases and invasive techniques for the detailed investigation. The methods used during each phase of investigation are discussed. Two case studies are then presented to provide examples of the investigative methods used in two different environments. The first being a flat featureless site with thick soils and deeply weathered bedrock, while the second is a mountainous site with differentially weathered rocky outcrops. Based on these cases, it is clear that an understanding of the geology and geomorphology of the site is vital to the final geotechnical assessment. Key words: Decline shaft, boxcut, geology, geomorphology, geotechnical, portal.

Jan 1, 2009

State ownership of mineral in the ground is not newthe Regalian Right is an ancient concept. And the compulsory purchase of land and the minerals beneath it by the State or a body approved by the State (Fitzgerald, 1952) was a principle well established and enforced in practice over a hundred years ago, when such powers became a practical necessity during the period of railway building in Britain and elsewhere:The acquisition of mineral properties which stand in the way of public construction projects still goes on. But in recent years nationalization is being increasingly undertaken as part of the planned use of national resources, for the closer regulation of economic activities, or merely, so it would seem, as a matter of political expediency or national pride. For instance, the unsevered coal in Britain came under State ownership in 1938 in an attempt to simplify a complex pattern of freehold titles which were impedingplanned mining operations. Later, unsevered minerals became a factor in negotiations arising under various town and country planning acts. The acquisition of the Rio Tinto mines by the Spanish Government implies political aspirations. Or State purchase may even be accidental: it was the easiest course for the Sierra Leone Government consequential upon its failure to prevent widespread trespass over legally-held diamond privileges in 1955.This paper has been prompted by problems that have arisen when properties containing unsevered mineral have been expropriated by the Crown in New Zealand: expropriations, it is true, that have been on a small scale in rela...

Jan 1, 1957

By Donald Bruce

The three types of specifications which are used for micropile work are: ? Performance Specifications: The contractor is permitted control over certain design and/or construction procedures but must demonstrate to the owner through testing and/or certification that the final product meets the specified performance criteria. This method allows and encourages the contractor to provide a competitive and/or innovative micropile design within the framework of the overall design requirements. The responsibilities for the work are shared between the owner and the contractor. ? Open Specifications: These leave the scope and design of the installation up to the micropile contractor. This method is the most common for securing bids on temporary micropile work. The responsibility for design and performance is clearly placed on the contractor. Open specifications are not recommended for permanent applications. This method allows the contractor to select the most economical micropile system. ? Prescriptive Specification: The Owner describes specific procedures that must be followed, but which may not necessarily describe the objective of the work. When prescriptive specifications are used, the owner is responsible for the proper performance of the system. The contractor is responsible for satisfying the details of the specifications. Performance specifications are the most common and best reflect the challenges and interests of micropile technology and applications.

Jan 1, 2004

By H. William Zeller

The U.S. Bureau of Mines evaluated the effects of two iron-based fuel additives on diesel particulate matter (DPM) emissions. The 5.6-L, six-cylinder test engine is typical of engines used in underground mines. One additive, ferrous picrate, did not measurably affect exhaust emissions. This report is mainly about a ferrocene-based additive that reduced DPM between 4 and 45 pet., depending on engine operating conditions. The report concludes that the DPM reductions were caused by the catalytic oxidation properties of a ferric oxide coating that developed inside the engine's combustion chamber. The ferric oxide coating also decreased gas-phase hydrocarbons and O2, but it increased CO2 and NOx, The increase in NOx, of about 12 pet, is considered the only adverse effect of the ferrocene-based fuel additive. The results suggest that the effectiveness of ferrocene was partially offset by increased sulfates because of the high-sulfur fuel used. Recommendations for continuing fuel additive research are presented.

Jan 1, 2010

By Joint Micropiles Committee

"The three types of specifications which are used for micropile work are: • Performance Specifications: The contractor is permitted control over certain design and/or construction procedures but must demonstrate to the owner through testing and/or certification that the final product meets the specified performance criteria. This method allows and encourages the contractor to provide a competitive and/or innovative micropile design within the framework of the overall design requirements. The responsibilities for the work are shared between the owner and the contractor. • Open Specifications: These leave the scope and design of the installation up to the micropile contractor. This method is the most common for securing bids on temporary micropile work. The responsibility for design and performance is clearly placed on the contractor. Open specifications are not recommended for permanent applications. This method allows the contractor to select the most economical micropile system. • Prescriptive Specification: The Owner describes specific procedures that must be followed, but which may not necessarily describe the objective of the work. When prescriptive specifications are used, the owner is responsible for the proper performance of the system. The contractor is responsible for satisfying the details of the specifications.Performance specifications are the most common and best reflect the challenges and interests of micropile technology and applications.The owner, designer and contractor will together be responsible for the tasks associated with the design, installation, acceptance, and performance of the micropiles. The installation of micropiles requires specialized equipment, techniques, and appropriate workmanship. Not every detail of the work can be specified, and not every potential problem can be anticipated. Therefore, a contractor who has demonstrated experience in micropiles must be selected to execute the work required."

Jan 1, 2004

By Paolo Heiniger

The aim of this paper is to present the operative solutions devised and then adopted to implement the underexcavation (soil extraction) of the Tower of Pisa, by means of soil extraction. The intervention has been performed by the Consorzio Progetto Torre di Pisa, a joint venture made of five qualified Italian companies (Trevi S.p.A. , Rodio S.p.A., Italsonda S.p.A., Ismes -Enel Hydro S.p.A., Bonifica S.p.A.), selected for their experience in the field of monitoring and restoration of monuments, structural design, foundation engineering and specialised works in underground conditions. Since 1991 the Consorzio has been charged with the specific task of implementing, within the contractual frame of a Concession, all the decisions made by the International Multidisciplinary Commission appointed by the Italian Government the previous year, with the aim at solving the «problem» of the Tower, strengthening the structure and stabilising its foundation. The Trevi Group, which is represented by Trevi S.p.A. in the above mentioned Consorzio, has given and is giving its direct and constant contribution and is engaged in supplying the special equipment to the operation and the drilling technology which has been successfully adopted to date.

Jan 1, 2000

By A. Roberts

This paper reviews progress in equipment design and in the techniques applied to mine lighting in Great Britain. The incidence of the disease miner's nystagmus, which was a major source of concern only a few years ago, has now diminished, largely owing to improvements in standards of lighting in mines. The reorganisation of the coal mining industry, involving increasing mech-anisation, together with new safety legislation, has brought about the widespread use of mains electric lighting underground. An account is given of some of the results of research to determine the lighting conditions needed for compliance with the compulsory legal requirement of "sufficient and suitable" general lighting at specific localities in British mines. Some details are given of the techniques applied and the results of recent research in the problem of glare from miners' cap lamps. Of the various factors in the working environment of the miner, it is true to say that lighting is seldom given attention comparable with that devoted to other factors, such as dust, heat and humidity, or atmospheric gas content. No doubt one reason for this lies in the ability of the human eye to adapt itself to low brightness levels. Be that as it may, the fact is that at the turn of the 20th century the miner's working light improved little throughout the centuries during which mining technology has developed. Indeed, in coal mines which encounter a methane explosion hazard, flame safety lamps, with a luminous intensity less than one candle power, were virtually the sole means of lighting during almost the whole of the 19th century. The 20th century has witnessed a substantial improvement in lighting techniques underground in coal and metalliferous mining. In Great Britain the general pattern has been one of standards periodically raised by the implementation of Statutory Regulations imposed under successive hlines Acts, but it is fair to add that the more progressive mining companies usually anticipated the Statutory Regulations, which when they have been put into effect have served to turn into general practice what was already being done at the better mines. In earlier years, official requirements were limited to the specification of approved lamp designs, with stipulated minimum values of luminous intensity and light output, but more recently the necessity of satisfactory maintenance of standards during service has been recognized, and the current regulations not only require that a maintenance organisation should exist, but also specify a maximum permissible depreciation below initial approval standards.'

Jan 1, 1961

By F. S. Young

Previous laboratory and field experimentation has demonstrated the effect of several variables on drilling rate.1-5 These results have been incorporated into optimization theories6-" for the purpose of reducing drilling cost. Minimum-cost drilling theories rely on a combination of historical data and empirical prediction techniques for selecting optimum bit weight and rotary speed. Past solutions have required extensive use of computing equipment because of both the complexity of the mathematical formulations and the large number of parameters involved. Field attempts to apply these computed results have frequently failed because of the uncertainty of input data requirements. Humble has developed an on-site computer system to control bit weight and rotary speed and thereby implement the concepts of minimum-cost drilling. This system can (1) perform short interval drilling rate tests for formation evaluation, (2) use the results of these tests as input information to solve minimum-cost drilling formulas, and (3) control bit weight and rotary speed in accordance with these computed solutions. The purpose of this paper is to describe the computer control system and present results of initial field testing. Theoretical Considerations Minimum-cost drilling (MCD) requires a quantitative evaluation of the variables involved. Several forms of a basic mathematical model have been sug-gested.'?,' "he relationships reported here form the basis for the solution programmed in this work. Four equations are used, expressing drilling rate, bit bearing wear, bit tooth wear, and cost. A solution for minimum-cost drilling assuming constant bit weight and rotary speed over the entire bit life has been programmed for use in computing MCD schedules. This solution is subject to certain limiting assumptions such as those discussed by Graham et a1.I2: 1. Drilling cost is the summation of bit cost, rotating cost, connection cost and hoisting cost. 2. Diamond bits are excluded. 3. Bit life is limited by either bearing failure or tooth wear, or by a combination of operational factors that make it cheaper to pull an incompletely consumed bit. 4. Circulating hydraulics are adequate and do not limit drilling rate. 5. Bit weight considerations exclude hole deviation. 6. Drilling rate is a function of only bit weight, rotary speed, and degree of tooth dullness; that is, the effects of pressure, lithology, fluid properties hydraulics and drill string dynamics are ignored. In equation form, the four MCD expressions are as follows:

Jan 1, 1970

By A. George Stern

The literature dealing with the drilling of oil wells has become extensive during the last few years, and oil men can find much information relating to drilling muds in the technical literature of the petroleum industry. Although large tonnages of clay are used in preparing drilling mud (also known as drilling fluid), almost no information has been published to apprise the clay industry of the types of minerals used, with their requirements and limitations. It is from this point of view that the present report has been prepared.

Jan 1, 1941

By John E. Conley

The need for lightweight aggregate for use in concrete products ,and structures has caused the Bureau of Mines to undertake an investigation to determine the availability of suitable raw materials and to study methods, procedures, and equipment to supply that need. Evidence is at hand to prove that the shortage of lightweight aggregate is nationwide. A survey recently covered in a report (13)5/ by the Construction Branch of the National Housing Agency has pointed out the locations in which lightweight aggregates are produced. A study of this information discloses that the producing centers are widespread, and that certain areas, notably the region east of the Mississippi River, and especially the sections along the Atlantic coast line and the Southeastern States, have only a few such plants. Certainly, many localities are badly in need of installations equipped to provide an ample supply of high-grade lightweight aggregate. The work undertaken by the Bureau of Mines includes investigation of the use of clays, shales, slate wastes, coal-mine wastes, diatomite-clay combinations, and various other 'mineral mixtures as possible raw materials. Likewise, special consideration has been given to the development' of equipment and techniques to produce the lightweight products.

Jan 1, 1949

Mine waste and mine reclamation are topics of major interest to the mining industry, the government and the general public. This publication and its companion volume are the proceedings of a conference held in Pittsburgh, April 19-21, 1988. There were nine sessions (50 papers) that dealt with the geochemistry, hydrology and problems of mine waste and mine water, especially acid mine drainage. These comprise Volume 1. The nine sessions (43 papers) that dealt with reclamation and restoration of disturbed lands, as well as related policy issues, are included in volume 2. Volume 2 also contains the ten papers that pertained to control of subsidence and mine fires at abandoned mines. Poster session presentations are, in general, represented by abstracts; these have been placed in the back of both volumes.

Jan 1, 1988

By Robert T. Davis

An award is a form of recognition given for superior performance in a special field of endeavor. Each year awards are given by the Joseph A. Holmes Safety Association and the National Safety Council to the coal-mining industry's underground and open-pit mines that have worked a specific number of man-hours without a lost-time injury. These awards have a dual significance in that they prove efficiency can be attained without injury to persons. Safety awards do not result from luck or good fortune but do result from sincere desire coupled with sufficient effort and cooperation to achieve a desired goal.

Jan 1, 1964