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The banded iron formations "jasper bars," jaspilites, banded hematite quartzites or banded ironstones, etc., as they have. variously been termed in Western Australia, constitute one of the most striking features of the Pre-Cambrian in this State. They occur in at least two distinct divisions of the Pre-Cambrian, viz., in horizons interbedded with quartzites, shales and thin bedded dolomite in the N~llagine (Proterozoic) Series; and amongst the Older Pre-Cambrian rocks, associated with the metamorphosed sediments of the Jimperding-Chittering Series, the Yilgarn Whitestone Series and the Mosquito Creek Series, and interbedded with metamorphosed basic lavas, tuffs and sediments of the Older prenstone or Kalgoorlie Series.In the Hamersley Ranges in the north-west of Western Australia banded ferroginous cherts are well developed amongst the horizontal sediments of Nullagine Age. These iron formations have recently sprung into prominence as they have been found to form the host rocks for important deposits of· blue asbestos. They are closely comparable with the unique crocidolite-bearing banded ironstones of the Cape Province, South Africa, and have been described elsewhere in some detail by the writer. (1) t .The banded iron formations with which it is intended to deal principally in the following pages, form most abundantly in the Central and Eastern Goldfields of Western Australia where they form portions of the Older Greenstone or Kalgoorlie Series of auriferous rocks. In these regions their chemical inertness and physical hardness provide considerable resistance to the agents of erosion and consequently they frequently stand out in strong topographic relief in otherwise monotonously flat or gently rolling country. These banded-iron formations have proved of considerable direct economic importance in the goldfields and in other portions of the State because of thei!! associations with 'gold, iron -and to' a lesser extent, manganese; whilst indirectly because of their peculiar nature, form and topographic prominence, etc, they have been of tremendous assistance to the field geologist both in the practical application of methods of geological mapping and in the' elucidation of geological structures. Finally, they have recently acquired a new importance in the specialised search for ore-bearing lodes or for structural information over areas of soil-covered country, as their form and composition make them ideal subjects for the use of either electrical or m!1-gnetic methods of geophysical prospecting.

Jan 1, 1941

By K. H. Hofer

La mecánica de rocas se basa en el descubrimiento de las leyes que siguen las perturbaciones del estado natural de la corteza terrestre provocadas por la actividad minera. En ese sentido, el presente texto señala la importancia de este proceso en la ciencia de la minería -en tanto revisa el comportamiento de la resistencia de la roca, determina el estado de las tensiones primarias de la corteza terrestre y analiza la repartición secundaria de tensiones provocadas por la formación de huecos y sus consecuencias sobre la roca en el espacio y tiempo.

Nov 1, 1971

By Stephan Großwig, Karolina Nycz, Arne Kindler

"Commonly used anchor monitoring systems are mainly based on the use of anchor force meters. However, experience shows that the reliability of the display of force meters lowers over time. Other measurement and test methods like for example fibre bragg grating method require a comparison with an unloaded optical fibre and give only selective information about the bearing behavior. Moreover the obtained information has to be interpreted. In the following article, first measuring results of an anchor monitoring system based on measurements with optical fibre are presented. The new monitoring system is based on the Rayleigh technology and was used to test the load bearing behavior of the anchor grout body as well as for the evaluation of the grout body condition in concrete-damaging groundwater.INTRODUCTIONThe first fibre optic sensors came onto the market about three decades ago. Initially used as special solutions only in selected cases, now they have found use in almost all areas of technology, especially in areas, where electrical sensor systems reach their limits. The first application examples of spatially resolved fibre-optic sensors in the field of geotechnics have been in existence since the mid-1990s, in projects such as the assessment of the of radioactive repository location sites (Hurtig et al. 1994), for the monitoring of landfill sealing systems (Hurtig et al. 1995) or within the framework of the rehabilitation of mountain farming landscapes (Schreck et al. 1998).The company's first own works in the field of glass fibre measurement technology have been in existence since 1993. The first carried out projects were a monitoring at the Edertalsperre (Dietz et al. 2001), a monitoring with glass fibre tendon at a flood bridge in Carinthia as well as monitoring within the framework of the Storebælt crossing. In all cases, the structure was permanently monitored by means of individual-point measurements. Since 1993 various fibre-optic sensor solutions for geotechnical applications have been introduced to the market (Voet, Glötzl 1996, Hurtig et al. 1994)."

Jan 1, 2017

By Howard Roscoe

Linking Ashford International Station to the new Channel Tunnel Rail Link required over 5000 rotary bored and CFA (continuous flight auger) piles to form tunnel walls and viaduct foundations and to support overbridges and trackside barriers.. Much of the work was carried out close to the existing railway infrastructure. Plunged columns were used to maintain traffic flows over the tunnel site during construction. The results of an extensive programme of vertical and lateral load tests on bored and CFA piles in heavily overconsolidated Weald Clay are compared to illustrate the relative importance of stress relief and of prolonged exposure to bentonite. The completion on schedule of this major piling and ground engineering contract (value £30 million) demonstrates that collaborative working in partnership produced cost effective solutions to a series of challenging technical and logistical problems.

Jan 1, 2002

By Irvin G. Burough

ANDROS INCORPORATED has designed, manufactured and delivered four handheld C02 DETECTORS and three handheld CH4 DETECTORS. These instruments are for in-mine safety use. The DETECTORS incorporated an NDIR optical/electronic analyzer design in which exceptional zero stability is achieved by pressure modulation of the sample gas. This eliminates the need for daily calibration. This stability and the miniature design (2.5" x 4.5" x 4.5"; 4.5 lbs) of the C02/CH4 DETECTORS provide practical instruments suitable for routine safety inspections. This report includes the theory and design of the instruments as well as studies of gas-pressure modulation by a piezoceramic-driven Helmholtz resonator.

Jan 1, 1979

By Jeon Jeon, Yong-Kun Choi, Chung-In Lee, Yong-Hun Jong, Hag-Soo Kim

In this study, a computer program to design tunnel blasting pattern has been developed. The program consists of two parts; one is for tunnel blasting pattern design and the other is for blasting modeling to estimate the peak particle velocity, the distribution of fragmentation and the excavation damage zone. We modified the design method of tunnel blasting pattern suggested by Langefors because it provided undesirable pattern in blasting practices such as considerably large center cut and too large burden for Vcut as drilling length increased. As a result, the burden and spacing were reduced to practically appropriate amounts. In addition, the correlation between rock mass rate, RMR, and rock constant in blasting, c, was analyzed based on the data collected from twenty three tests of tunnel blasting. It was concluded that the correlation between them was fairly good enough to be applied in cut design. In order to check the validity of the modified methods and their practical applicability, test blasting was carried out at two different tunnel construction sites in Korea. The results were satisfactory in that the average rate of advance was 90% and the overbreak did not cause additional support. Futhermore, the developed program is capable of estimating peak particle velocity by using (a) the existing vibration equations, (b) the vibration equation obtained by test blasting to check out the practical applicability of the designed blasting pattern. Feedback is implemented into the program to adjust the designed blasting pattern and control the vibration.

Jan 1, 2005

Reduce the potential for injuries in underground mines by providing an alternative to manually lifting and holding heavy roof-support beams. The Problem I-beams, rail sections, and wooden cross-beams are often used in mine haulageways where extensive roof support is needed. Studies by the Bureau of Mines have shown that many mines must resort to manually lifting, moving and installing these beams. Such manual-handling activities have the potential for causing injury to mine workers, particularly back injuries. I-beams used for roof support can typically weigh from 400-500 lbs. Rail sections weigh about the same as the I-beams. Wooden beams can weigh from 200 to 300 lbs. To lift a single beam usually requires the efforts of 3 to 5 mine personnel.

Jan 1, 1988

By E. Snyders

The upgrading process of an inferior grade of zircon to a superior opacifier for ceramic applications was investigated. A calcining process in the presence of mineralizers was used to produce the product in a conventional muffle furnace. A pre-milled inferior grade zircon concentrate, with a relatively high iron and alumina content generally not suitable for high quality ceramic applications, was used in this study. The influence of the upgrading process on the opacifying properties of the zircon material was compared to that of commercially available prime grade zircon opacifier products currently being produced in South Africa. The influence of a calcining step in the presence of mineralizers with regard to the milling characteristics of the treated zircon material was also evaluated in this study. The morphology of the treated and untreated zircon opacifier samples were investigated by SEM micrographs and the colours of zircon samples were characterized on the grounds of the Commission Internationale de l`Eclairage (CIE) standard procedure (CIE L* a* b* measurements) after application on a bisque ceramic tile. It was found that the treatment improved both the milling as well as the opacifying properties of the treated inferior grade zircon concentrate and renders it equivalent to or better than prime grade zircon opacacifiers currently produced. Keywords: ZrSiO4; opacifier; colour; milling; calcining.

Jan 1, 2005

By Harry Schnabel

A 6200 m² cement deep soil mixed (CDSM) wall was constructed for an addition to the Museum of Fine Arts in Boston, Massachusetts. The addition was located along the east side of the existing museum within an existing courtyard and in the area of a recently demolished structure. The basement for the new addition extended up to 9.1 m below the floor slabs of the adjacent buildings. The adjacent buildings are supported on a variety of foundations including; shallow spread footings on alluvial sand deposits, low capacity piles bearing in the alluvial sands and Boston blue clay, and caissons bearing on the alluvial sands and clay. Groundwater was less than one meter below the top of the CDSM wall. The new addition was founded on shallow foundations in the desiccated crust of the Boston Blue Clay. The CDSM wall was selected as the most economical means to control deep seated ground movements, limit movements of adjacent structures, and inhibit groundwater flow into the excavation. Braces and a continuous wale were used to support the CDSM wall where it was located adjacent to structures. Tiebacks were used where there were no structures. Other geotechnical construction at the site included: ? Jet grouting (JG) to improve the ground and provide an impervious subgrade layer at the west end of the addition, ? Concrete pier underpinning was used to support an existing structure on the west end of the site, and ? A secant pile wall using alternating drilled shafts and jet grout columns was used for earth support and a barrier to groundwater flow to allow for the installation of a storage tank at the south end of the site. Inclinometers, total station surveying, vibrating wire strain gauges on the braces and wales and load cells on the tiebacks were used to monitor performance of the excavation support system. The excavation support system performed better than required limiting lateral movements of the adjacent structures to less than 13 mm and vertical settlement to less than 8 mm. No settlements or movement were detected during the construction of the wall. Lateral movement of the CDSM wall was typically below 15 mm with the maximum movement occurring near subgrade.

Jan 1, 2011

By C. E. Julihn, Lowell B. Moon

"INTRODUCTION To increase the supply of ore needed to produce steel the Bureau of Mines has explored 187 mineral deposits containing chromium, iron, manganese, cobalt, nickel, fluorspar, tungsten, vanadium, or coal during the fiscal years. 1940-44, the deposits thus explored were selected from several thousand that were first examined to appraise their possibilities. The objective of the exploration was to determine the tonnage and grade of ores upon which mining, operations might be based, and the metallurgical processing that was most suitable for their utilization.Most of these deposits were sub-marginal by pre-war standards; hence there had been no incentive for their exploration, yet many such deposits were known to exist that probably contained ore sufficient in grade and amount to be utilized as war reserves.Some of the Bureau's exploration projects have disclosed substantial or even very large amounts of ore, much of which is fairly high in grade. In a few of them bodies of high-grade ore have been found, though in others the tonnage has proved to be too small or too low-grade for utilization."

Mar 1, 1945

By Rapheal Trousselle

For over 5 years, Davey Bickford has been developing and testing an electronic detonator blasting system. These new-technology detonators provide more accurate timing than conventional systems that rely on the combustion speed of a pyrotechnic composition.

Jan 1, 1997

By D. M. Doyle

"In this paper I will summarized the Falconbridge Nickel Mines1) energy costs and consumption data by fuel, process, cost centre and estimate our future costs and consumption patterns 2) detail the distribution of electrical energy 3) distribution of other forms of energy 4) describe present and planned energy conservation schemes; and 5) discuss economic justification and responsibility.There is sufficient material in this presentation to warrant several technical papers, however we felt that an overview of all our data and endeavors on the subject, would be most beneficial to those companies formulating energy conservation plans. The data briefly referred to in this slide presentation can be found in the technical paper.Over a five year period, total energy costs will vary between $63 and $94 MM depending on the future rate of energy cost escalation. An unrealistic 32% reduction in energy consumption is required to hold our own in the years ahead whereas an attainable 10°;, reduction in energy consumption would save $9 MM over this five year period.Total energy consumption, tonnage of ore delivered to plants and their ration BTU’s per ton of ore, are graphed for the years 1973 through 1976 and forecasted for the 1980’s. In 1974 we along with other member companies of the Mining Association, determined our purchased energy per ton consumption rate and set, as our goal, a 20% reduction by 1980. The dotted lines calculated from the energy audit, based on 1976 data shows there is a potential for a 10% increase in energy per ton. This could result from a lower than forecasted mining rate and operation of the new roasting, electric furnace and acid recovery facilities installed for environmental considerations at designed capacity."

Jan 1, 1978

By Hasan Ozturk

Laboratory testing examined the effect of a variety of intrinsic rock properties and environment conditions that influence the adhesive bond between rock and thin spray-on liners. The liner materials used for these tests were Tekflex, provided by Fosroc, Castonite, provided by Rohms and Haas Co., Rockweb provided by Spray-on Plastics, and CS 1251 2K, provided by Master Builders. Some of the variables examined include: rock strength (tensile/compressive strength) rock mineralogy, rock surface roughness (grain size, fracture/joint roughness), and surface contamination (oil, water or dust). Under optimal conditions, adhesive strengths reaching at least 3 MPa can be achieved. Where the rock surface is contaminated with dust or the rock is weak in tension, it may be difficult to reach adhesion strengths of 1 to 1.5 MPa.

May 1, 2004

By Don C. Warrington

This paper is a survey of the various methods and research efforts by which the drivability of piles is determined. First, a brief outline of the basic theory and the important parameters for driving by vibration are presented. Then, a wide variety of methods by which the drivability of piles is determined are presented and discussed, with special emphasis on methods developed in the USSR. Each of these methods are examined as to how they take into account the various parameters of vibratory pile driving, such as eccentric moment, frequency, dynamic force, motor torque and power, vibrating and static weight, and other variables. Some relation of these methods of field data is presented as well.

Jan 1, 1989

By R. Q. Honaker, D. P. Patil, A. Sirkeci

Due to increased production of fine coal during mining during this century and inefficient fine coal recovery technologies, a vast reserve of high quality coal currently exists in refuse ponds. A novel fine coal circuit consisting of a hindered-bed classifier, an enhanced gravity concentrator and a flotation column has been evaluated for the recovery of fine coal from refuse ponds. The treatment of a pond derived from Pittsburgh No. 8 seam coal resulted in the production of a premium fuel containing less than 5% ash and a calorific value of about 30,173kJ/kg with 60% mass yield. The results from the treatment of two refuse pond materials will be presented in this publication.

Jan 1, 2000

By W. M. Dressel

The Federal Bureau of Mines has obtained data by differential thermal analysis of the various minerals that represent the nation's resources in manganese. These data are supported by X-ray diffraction analysis, chemical analysis, mineralography, and optical mineralogy, and provide fundamental information on the response of each mineral to thermal treatment in oxidizing, reducing, and neutral atmospheres. The information can be applied advantage¬ously in the identification of manganese minerals. Its greatest potential value, however, lies in the application of the quantitative data on the reaction temperatures, rates, and products to the more efficient extraction of manganese from U.S. ores. Thermal analysis curves are presented for certain manganese minerals, namely hausmannite, bixbyite, braunite, pyrolusite, lithiophorite, cryptomelane, hollandite, manganite, rhodochrosite, and rhodonite. The original minerals and the products of their thermal decomposition were identified by X-ray diffraction analysis, supplemented by chemical analysis and mineralogical identification.

Jan 1, 1961

By Varadarajan Seshadri

Geometallurgical characterization of iron ore which is a raw material for Iron making as in the case of charcoal blast furnaces operating in Brazil or for production of agglomerates such as iron ore sinter which serves as burden material for blast furnces of high productivity or pellets extensively used in the direct reduction processes all over the world in the iron and steel industry. Selection of proper raw material after due characterization should lead to an improvement of the productivity of the respective processes The usual classification of quality of iron ore is uniquely based on chemical analysis, granulometric and physical parameters. However not much emphasis has been given to the structural characteristics which also are important in the processes. Different typological categories of Brazilian iron ores have been used in the characterization . For instance, several kinds of hematite crystals like specularite, martite and microgranular hematite, etc with variable crystal sizes are found in the different ore types. They are also composed of different of fabrics and types of accessorial mineralogical constituents and have different porosities, pore diameters, etc which influence the cold and the hot agglomeration stages of the ore fines, and also chracteristics such as reducibility, decrepitation etc, important for assessment of quality of iron ores. . The first step for attaining a good characterization of ores is to know in detail about the structure of the deposit, shape of the body, types of iron ores and their distribution. This requires a geological-structural study and the mapping of the bodies using mineralogical criteria for typological classification of ores. followed by structural characterization of materials in stages of mining, comminution, screening and concentration processes. In this contribution a geometallurgical approach for quality control of Brazilian iron ores for sintering and pelletizing processes is highligted.

Jan 1, 2006

By K. Tabra

In a mine operation, the proper strategy to handle residues is one of the main concerns, in particular when dealing with mine/plant liquid effluents. Most active water treatment systems at metal mines rely on standard alkali-addition procedures. However, the increase of mineral prices, stricter environmental standards and high metal content in some effluents, has led to the development of alternative treatment techniques for their removal and/or recovery. This article presents a roadmap to face mine wastewater treatment requirement, with focus on two active treatment strategies: 1) conventional lime-based technology and 2) the use of NaSH or Fe(OH)3 for metal precipitation and separation, including possible valuable elements recovery. The Roadmap consists of 1) Approach to effluent treatment 2) Characterization 3) Precipitation tests 4) Solid/liquid separation tests and 5) Economic analysis.

Feb 27, 2013

By Bradford F. Townsend

A study was made on six collapses that occurred during large-diameter tunnelling through weak sedimentary rocks and soil using SES methods in three stages?top heading, bench and invert. The collapsed lengths are between 20 m and 277 m. The collapses were re-mined using essentially the same tunnel-ling method with larger excavation profiles to accommodate the designed remedial measures consisting of ground treatment, pre-support and stronger initial support/outer lining required to carry higher ground loads acting in the collapsed lengths. The paper presents information on the collapses and the design and execution of the remedial measures.

Jan 1, 2008

By F. A. Rutledge

[An a part of the United States Department of the interior program for the development and use of Alaska raw materials, the Bureau of Mines is conducting an investigation of deposits of nonmetallic minerals accessible to the Alaska Railroad for use in building; materials is In the Alaska Railroad-belt area. The results of the investigations, to date, indices that raw materials for the preduction of brick products are in plentiful supply as cloy in the Anchorage area, as fire clay at Sheep Mountain, and as shale in the Healy Creek coal formations near Healy, Alaska.]

Jan 1, 1953