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By Carlton E. Brown

Broom and Yant6/ recently described a. microprojection method for determining the particle-size distribution and number concentration of samples of dust collected from the air by such samplers as the Owens jet dust counter) and the thermal precipitator8/ . This method was developed to obviate or reduce the eyestrain consequent to the regular filar-micrometer method9/ and to save time and work. The article stated that work was in progress on a micrcprojection method for counting impinger dust samples; this article describes the method developed. ACKNOWLEDGMENTS The assistance of the personnel of the ventilation Department of the Anaconda Copper Miring Co., Butte, Mont., in developing this method and particularly in suggesting a suitable material to use for the microprojector screen is sincerely appreciated. Much of the work was done in the laboratory of the Anaconda Copper Mining Co. on samples collected in Butte mines during a cooperative study with this Bureau.

Jan 1, 1938

By O. A. Carson

"IntroductionTHE ZINC-BASE die casting alloys in common usage contain approximately 4 per cent aluminum as the major alloy element. In addition, they contain about 0.05 per cent Mg .and may• have a small amount .of copper. These are usually the only •elements intentionally present.Small amounts of some impurities have been shown to have a deleterious effect on the properties of these alloys and therefore the impurities are kept low by starting with '99.99%' zinc.The reasons for holding the aluminum content at 4 per cent are not clear. Some statements appear in the literature that higher aluminum increases the brittleness, but probably the chief reason was the relative price of zinc and of aluminum when 4% alloys became firmly established. At that time, aluminum was three to four times the price •of zinc on a weight •basis. Recent prices, roughly equivalent per lb., make aluminum considerably cheaper than zinc on a volume basis and suggest that increased aluminum content would result in a decrease in the cost per piece due to the lower density of the alloy.Little information could be found in the literature and, therefore, it was decided to determine some physical properties of the higher aluminum zinc-base alloys made from high-purity zinc."

Jan 1, 1953

By E. J. Kloos, R. H. Schutz, B. I. Ferber

To Assist users in the selection of reliable and satisfactory respiratory protective devices, the Bureau of Mines has established five schedules of minimum performance requirements for the approval of respirators . The current revisions of these schedules include 13D for self-contained breathing apparatus, 14F for gas masks , 19B and the amendments to 19B for suppliedair respirators , 21B for dust , fume, and mist respirators , and 23B for chemical cartridge respirators . Copies of these schedules may be obtained from the Bureau of Mines, Publications Distribution Section, 4800 Forbes Avenue, Pittsburgh , Pa . , 15213 . Approval tests on respirators are performed only at the request of the manufacturer of the respirator and at his expense. If the device meets the approval requirements , a certificate of approval is granted on the complete respirator. This certificate states that as long as the respirator is manufactured as originally approved, or in accordance with any changes covered by an extension of the original approval, the manufacturer may advertise and sell his respirator as being approved by the Bureau of Mines. Many industries and regulatory agencies require that respirators approved by the Bureau of Mines be used where respiratory protection is needed. The Bureau of Mines, however, has no regulatory power over the use of the respirators that it approves. It acts as an impartial testing agency to insure the availability of suitable and safe respirators. At frequent intervals, the Bureau of Mines purchases approved respirators and replacement parts on the open market. These are examined for conformity to the approved status, and are checked to insure that the manufacturer's production facilities are maintaining a satisfactory quality control .

Jan 1, 1966

By W. A. Clark, E. H. Dresser

ORE from the Minnesota iron ranges is transported from the mines to the loading docks on Lake Superior over four different railways: the Great Northern, Northern Pacific, Soo Line, and Duluth, Missabe and Iron Range, with hauls varying from 60 to 110 miles. For this service a large amount of specialized equipment is used. The steel ore cars are of the hopper type, 24 ft. long, to dump into alternate pockets of the docks, these pockets being 12 ft. long to correspond with the 12 or 24-ft. spacing of the boat hatches. The more recently con-

Jan 1, 1941

By Z X. Zhang

If the iron ore loss is 15% in the process of mining, the total iron ore loss in the world will be about 461 million tons, this is equal to the total production of 230 iron ore mines each of which produces 2 million-tons of iron ore per year. Based on a series of blast tests in the Malmberget mine, this paper shows that ore recovery can be markedly increased by improving blasting technology such as choosing a correct primer position and making use of shock wave collision. The paper further suggests that a high ore recovery can not only reduce natural resource loss and mining cost but also prolong the life of a mine. In addition, the paper shows an example of reducing blast-caused rock damage in the roofs and walls of underground drifts (tunnels) by using new blasting methods in the Malmberget mine. Finally, the paper shows how the Malmberget mine has successfully reduced the ground vibrations, without adversely affecting fragmentation and ore recovery in sublevel caving mining.

Jan 1, 2014

By C. H. Mathewson

CONSIDERABLE progress has been made during the last few years in analyzing the action of plastic deformation in metallic crystals. This is due largely to the development of X-ray spectrographic methods for studying changes in the orientation of single crystals, or of conglomerates, as they occur during the process of plastic deformation, but partly to the widespread knowledge of suitable technique for preparing large (single or variously combined) crystals for direct crystallographic observation under stress or in various conditions of strain. These two methods of studying changes in the crystalline structure of metals may of course be used in conjunction with features of mutual support, but unfortunately the advantage of direct crystallographic observation is lost when we proceed to the study of severely cold-worked structures, owing to the occurrence of real or apparent crystalline discontinuities which become more and more complicated as the amount of plastic action increases. Furthermore, the X-ray methods do not appear to be adequate, at least in their present stage of development, to fix definitely the character of structural alteration in the parent crystal lattice by plastic deformation. The principal question at issue concerns the nature of the crystalline particles that remain after plastic deformation. These are generally known in our American metallurgical literature as crystalline fragments,' and they seem, indeed, to diffract as individuals causing the Hull pattern of a severely cold-worked metal to resemble the pattern of a fine powder,2 with certain features of preferred orientation among the particles deter- mined by the manner and intensity of cold working. We must freely concede that there are conceptions of lattice alteration, apart from that of simple fragmentation, which would account for an increasing number of lattice positions according to X-ray spectrographic observation as the degree of deformation increased.

Jan 1, 1927

By David Hartley

United States Steel Corporation Minntac Mine is located at Mt. Iron, Minnesota, on the Mesabi Iron Range. The taconite pit is two miles long by a mile wide, with a maximum depth of 170 feet. This paper will deal with the radio remote control of locomotives engaged in the railroad haulage of crude ore and waste rock at this property.

Jan 1, 1970

By Edward H. Robie

PONCA CITY proved an ideal selection as a place of meeting for the Petroleum Division this fall. The accommodations at the Conoco Club were just what was required for such a gathering; the committee having the arrangements in charge functioned with the efficiency of veterans and the enthusiasm of neophytes; and the members and guests followed the speakers with close attention, entered the subsequent discussions with gusto, and divulged the "low-down" at private conferences. No one minded the drizzling rain on the first day, which only served to keep up the attendance in the auditorium; the weather then cleared up in time for a group picture before the gathering went their separate ways.

Jan 1, 1932

By RUSSELL S. DAVIES, Andrew Allan, John W. Buch

This is a progress report for the period February 1, 1949, to August 15, 1949, covering experiments with lightweight shearing machines for developing thin, steeply pitching anthracite beds. The over-all objective at the time an underground test section was established on July 30, 1946, was to improve mining above the gangway by developing methods for mechanization of pitch mining. Following the preliminary cutting tests in the gangway with the German machines, it became evident that the use of machines of this type indicated advantages for development work that could not be overlooked and warranted investigation. An agreement was reached with the cooperating company that this be done. Thus, the objectivo in the period covered by this report has been to obtain operating data to uso in comparing hand and machine methods of driving development openings. In obtaining the machine-mining data, 78 feet of gangway, 108 feet of heading, and 80 foot of chute work were driven. Hand-mining data are authentic for the mining condition. It has been shown that full mechanization is two and one-half times as fast as conventional hand methods on a lineal-feet- advance-per-shift basis and costs but little more than one-third as much. Tho machines are air-powered; there is less shattering of the coal bed by blasting; water sprays are used to allay' dust; coal is loaded by machine; no rock is taken; timber is not dislodgod by heavy blasting charges; and it may be said, except for the development of a means for transporting timber to the face, that the tasks for the miner are less arduous, and the working face equally as safe, or safer, than in driving by hand. Face timbering remains the greatest time- consuming cycle item, and steps are being taken to correct this. More than 50 percent of the cycle time is now usod for face-timbering work.

Jul 1, 1951

By J P. Barkas

World demand for iron ore is far from peaking, and the substantial price decline that has captivated commentators since early 2014 is not the result of widespread misreading by producers of the prospects for global market growth. Recent price movements provide little useful insight into the industry’s longer-term fortunes, apart from reminding mining companies that their businesses need to be robust against the volatility and inescapable cyclicality of mineral commodity markets. It is timely to take a strategic view of the history and longer-term prospects for the iron ore industry and of Australia’s place in it.CITATION:Barkas, J P, 2015. Perspectives on the long-term outlook for iron ore, in Proceedings Iron Ore 2015, pp 3–6 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By R. G. Knickerbocker

A STURDY and consistent expansion of the metal industry occurred in 1947 exemplified by an increase of approximately 30 per cent in steel consumption over 1946. For this major reason, ferroalloy metals have seen their most useful and important peace-time year. The current domestic rate of consumption of high-grade ferroalloy ores, together with added consumption of new foreign producers as well as for eign nationals' restrictions on high-grade exports, makes very evident the increasing difficulties of obtaining sufficient high-grade ores. This accentuates the need for new and less expensive methods of production of ferro-alloy metals of higher purity from lower-grade domestic resources. As an important factor in preparedness, procurement of these high-grade, -critical ferroalloy minerals and metals for our nation's stock piles is a most important task. Also, this stock-piling can be the means of supplying incentive for the industrial development of the new metallurgical processes and plants necessary for the recovery of ferroalloy metals from our domestic low-grade deposits.

Jan 1, 1948

By R. S. Farinato

Thionocarbamate flotation reagents have enjoyed a niche position in the recovery of copper sulfides and activated sphalerites since their introduction in the mid 1950's (Harris, 1954). Thionocarbamates containing an allyl group (-CH2- CH=CH2), introduced recently Lewellyn, 1985; Nagaraj, 1988; Avotins, 1991), are used commercially as collectors for copper sulfides and activated sphalerite. Laboratory flotation tests and plant usage have demonstrated that allyl-containing thionocarbamate collectors exhibit certain unique properties that distinguish them from the corresponding dialkyl thionocarbamates. Spectroscopic (FTIR, XPS) and wettability studies of N-allyl iso-butyl thionocarbamate (AIBTC) and its saturated analog N-propyl iso-butyl thionocarbamate (NPIBTC) adsorbed on copper at pH 9 were performed in order to investigate whether there were any fundamental reasons for these differences. Flotation tests were carried out on chalcocite, copper ore and an activated sphalerite.

Jan 1, 1993

By Ashraf A. M. A. Wali

Many of the economic resources of Egypt have been recognized and exploited for thousands of years (e.g. gold and copper). Most of these minerals, particularly those from hard-rock sited deposits, are found in complex form along with other components while those present in sedimentary sequences are largely in simple compounds or as native elements. Recognition of their characteristic settings (structure, basin development, environment of formation etc.) is the main clue in predicting and locating their presence. The main economic minerals exploited in Egypt today come from sedimentary sequences and include sodium and potassium chlorides, gypsum, sulfur, and sedimentary iron ores. Large amounts of low grade sedimentary phosphates are known but are not of economic value at today's prices. Recent intensive investigation in the north-eastern Sinai (EI Arish) and along the southern coasts of the Gulf of Suez has revealed new and extensive sulfur and chloride deposits, and considerable oil and gas are now being exploited from closely related sediments. Tin is the only mineral that is produced from hard-rock sources, and gold and copper deposits are present but not of high enough grade to be economically viable. However, a significant part of Egypt has not yet been studied in enough detail to close the door on future discoveries. Another point of considerable geological interest is the presence of diverse, modern evaporitic settings, from which we may draw the analogs for many of the older gypsum, anhydrite, chloride and sulfur de-posits. In fact these analogs are so well displayed that both the Sinai and Gulf of Suez-Red Sea evaporites (Middle and Upper Miocene) can be readily compared with these modern deposits.

Jan 1, 1990

By R. Charlier, G. Radioti, J. -P. Radu, S. Delvoie, F. Nguyen

"In order to investigate the fracturing of the bedrock and its possible heterogeneous distribution in situ, four boreholes equipped with double-U geothermal pipes of 100 m long were installed on the campus of the University of Liege (Liege, Belgium) over a surface area of 32 m². The bedrock, which starts at a depth approximately of 8 m, is quite fractured and consists mainly of siltstone and shale interbedded with sandstone.Different geophysical methods are applied at two different phases, after drilling the boreholes and after injecting the grouting material. The first approach consists in lowering an ultrasonic borehole imager (borehole televiewer; Zemanek, Glenn, Norton, & Caldwell, 1970), an instrument that acts as an ultrasonic transducer and receiver, into the boreholes to obtain high-resolution, continuous images with 360° coverage of the local geology and fracturing. Moreover gamma-ray logs of the four boreholes are obtained and inclinometry is conducted.After drilling the boreholes fiber optic cables are attached along the pipe loops and the double-U pipes are installed inside the boreholes. Then the grouting material is injected. The second approach consists in measuring the temperature along the fibers by applying the Distributed Temperature Sensing technique (Soto, Sahu, Faralli, Bolognini, Di Pasquale, Nebendahl, & Rueck, 2007). A laser pulse is injected into the optical fiber and the temperature along the fiber is determined by the intensity of Raman stokes and anti-stokes reemitted signals. Temperature evolution is measured during hardening of the grouting material. Local maxima of the temperature curve are probably due to a local lower thermal conductivity and/or a local larger quantity of grouting material due to gathering of fractures.A detailed fracture characterisation (position, opening, orientation, dip angle) is obtained based on the acoustic signal travel time and amplitude. The fractures are characterised by the same dipping and orientation but significantly vary in number and location in the four boreholes, despite the close distance between them. Gamma-ray data and observation of the cuttings during drilling result in rock identification through depth as well as in determination of the layer dipping. The inclination of the four boreholes tends to be perpendicular to the dipping. The combination of the two geophysical methods as presented provides information useful for the hydro-thermo-mechanical behaviour of the bedrock. The contribution of the thermal behaviour of borehole heat exchangers to bedrock investigation will be further studied by conducting Distributed Thermal Response tests (Fujii, Okubo, & Itoi, 2006). During the tests we will measure the temperature variation thanks to the installed fiber optics. These data will allow us to correlate any anisotropic thermal behaviour to the geological characteristics. The available information could be used for a detailed numerical model."

Jan 1, 2015

By Richard H. Singleton

Native asphalt was produced in 1978-79 by six companies in four States. Leading States were Texas and Utah. Output in-creased 37% in 1978 to 1.7 million tons and decreased 5% in 1979 to 1.6 million tons while value increased 39% in 1978 to $19.3 million and 33% in 1979 to $25.6 million. Bituminous limestone was produced by Whites Uvalde Mines and by Uvalde Rock Asphalt Co. in Uvalde County, Tex.; by Southern Stone Co. in Colbert. Ala.; and by Barton County Rock Asphalt Co. in Barton County, Mo. The product was used mainly in street and road repair. Gilsonite was produced by American Gilsonite Co. in Uinta County, Utah, and by Ziegler Chemical and Mineral Corp. in Weber County, Utah. This material was used for purposes other than road repair.

Jan 1, 1980

By David R. Sutfin, Joseph Lodde

110 N. Carpenter is new commercial building located in the West Loop neighborhood of Chicago, Illinois. The new home to the McDonalds Corporation work headquarters, accelerated project delivery methods were essential to meet the scheduling demands for this project along with other projects slated to start in the region. As such top-down construction methods were utilized to allow for above and below grade construction to proceed in parallel in lieu of more conventional bottom-up construction methods, thus compressing the project schedule. To achieve this plan, perimeter secant pile walls were constructed in conjunction with interior columns/drilled shafts and a shear wall core constructed from inside a temporary cofferdam. The use of secant pile walls allowed for efficient accommodation of a variety of loading conditions including: exterior curtain walls loads, perimeter column loads, tower crane foundation loads, and in-plane shear loads. Furthermore, this system allowed for efficient and fluid operation of equipment on site in order to accommodate the 90-day window allotted for initial foundation construction. INTRODUCTION 110 N. Carpenter is a recently-constructed 9-story commercial building located on the old Harpo Studios property in the West Loop neighborhood of Chicago, IL. The construction of this 55,750m2 (600,000 ft2) structure is significant to the continued commercial development of Chicago as nearly 46,450m2 (500,000 ft2) of the building houses the new world headquarters for the McDonald’s Corporation, which had moved from Chicago to the suburb of Oak Brook in 1971. McDonald’s recommitment to this urban environment is not only a reinvention of the long-established fast food giant but the anchor for a broader redevelopment of the West Loop neighborhood. Since the opening of this building was seen by the developer, the City of Chicago and others as a key to future local projects, innovative solutions were required to showcase forward-thinking design as well as expedite the construction process. The final result of the design/planning process is a structure consisting of nine levels of above-grade commercial space and two levels of below-grade parking, providing approximately 300 parking spaces. The above-grade structure consists of a reinforced concrete flat plate system, including two-way slabs, columns, and two core/shear wall systems for lateral support. With an average depth of 7m (23ft), the below-grade structure consists of interior components similar to the above-grade structure (structural slabs, columns, shear walls) but includes a perimeter secant pile wall that was designed to support lateral earth pressures; vertical forces from the exterior curtain walls, perimeter columns, and the construction tower cranes; and in-plane lateral forces to reduce the demand on and quantity of interior shear walls. The use of a secant pile wall is a key component to the project because it accommodated the use of top-down construction methods to accelerate the construction schedule.

Jan 1, 2019

By Jamal Rostami

With the recent technological advances; Tunnel Boring Machines (TBM) have become a viable economic alternative to drill and blast in hard rock excavation. These machines are finding increasing use in underground mine development due to the potential benefits they offer. The successful application of TBM technology to mining depends on the selection of the most suitable equipment and cutting tools for the rock and ground conditions to be encountered. In addition to required testing and geotechnical investigations, cutterhead design optimization is an integral part of the machine selection to assure a successful application of the machines in a specific project. This paper presents and discusses the back-ground of TBM application in a mining environment and the lessons learned, the process of conducting site investigation and the necessary laboratory testing together with machine selection and performance estimation for TBM use III mine development.

Jan 1, 1997

By Jürg Künzle

The use of the underground space has been a recurring issue in human history, whereas the reasons for building subsurface structures have changed over time. In the decades to come, the world will be marked by a variety of underground projects never before seen. This paper describes a series of characteristic challenges of designing and building underground freight transportation systems, with reference to the example of Cargo sous terrain, a privately funded underground logistics project in Switzerland. It provides an overview of contracting practices that allow these challenges to be addressed with success.

Jun 13, 2021

By Matthew Kowalczyk, Steve Bloomer, Peter Kowalczyk

"Mineral deposits found near seafloor hydrothermal venting are of great economic interest. Valuable metals such as gold, copper, zinc, and other polymetallic sulfides are found in appreciable grades in seafloor massive sulfide (SMS) deposits associated with these vents. For mapping these deposits, electromagnetic prospecting is one geophysical method that is very useful because copper/gold rich deposits are highly conductive.Ocean Floor Geophysics (OFG) in 2008 developed the first EM system to successfully map the limits of conductive mineralization in a survey at the Solwara 1 deposit (Kowalczyk, 2008). Since then, towed coincident loop time domain systems have been developed by Waseda University (Nakayama and Saito, 2016) and have successfully detected known mineralization buried at 30m depth. Using a deep tow controlled source electromagnetic (CSEM) array, very clear anomalies have been measured (Murton, 2017) over known mineralization at the TAG field on the mid-Atlantic ridge.In 2014 and 2015, OFG partnered with Fukada Salvage and Marine Co. Ltd. and the Scripps Institution of Oceanography to map methane hydrate deposits off the coast of Japan using a towed controlled source electromagnetic (CSEM) system developed by Scripps. These hydrate deposits are resistive targets, and the Scripps system successfully mapped subsurface electrical resistivity distributions to depths of several 100 metres below the seafloor. OFG is attempting to extend the Scripps CSEM technology to map subsurface conductive SMS deposits to a similar range of depths below the seafloor."

Jan 1, 2017

By Howard F. Puariea

This paper is one of a series describing methods and costs of recovering sand and gravel from alluvial deposits in the United States and deals directly with the methods employed by the Portland Gravel Co. in operating a clamshell dredge on the Willamette River near Portland, Oreg., and a pump dredge on the Columbia River near Vancouver, Wash. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local expenditures only and not total production costs. It is recognized that publication of total costs may in some instances cause embarrassment to individual producers as well as to the industry as a whole. On the other hand operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue.

Jan 1, 1932