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By F. R. Lee

[WHEN the Bureau of Mines was established in July 1910, one of the problems immediately attacked by the new organization was the development of standard, for the design and testing of electrical equipment that could be used without fear of initiating fires and explosions in underground coal mules. Research and investigation by Bureau personnel, supplemented by the published results of similar work by European mining authorities, led to the establishment of standards or "schedules." which guide manufacturers in the design of many types of electrically operated machines and devices used in. underground coal Mining. By issuing these standards, Bureau personnel establish the requirements to be met by such equipment before it tan be approved by the Bureau of Mines as permissible for use in gassy coal mines. Every 2 years the Bureau of Mines publishes a list of equipment that leas been accepted as approved or permissible during the preceding 2 calendar years. This is done to inform the mining industry of the availability of the latest equipment for safe use underground.]

Jan 1, 1964

By F. H. Cornet, D. Ask, O. Stephansson

We have conducted a stress analysis of overcoring stress measurements undertaken at the Zedex Test Site (ZTS) in the Äspö HRL, Sweden. Two different types of overcoring cells have been used at the site: the 9-gauge Borre Probe (CSIR-type) and the 12-gauge CSIRO HI cell. Inversion programs based on the least-squares criterion were developed and calibrated. The primary and secondary stress field in the ZTS were back-calculated using strain data from individual cells as well as from combining data from both cells. We propose that the combination of strain data from the two cells significantly improves the determination of the stress field. A striking result is the good agreement between the re-analysed overcoring data and the existing hydraulic fracturing data. The deviations for the horizontal stresses between the re-analyzed overcoring data and the existing hydraulic fracturing data are approximately 3 MPa. The deviation in the orientation of maximum horizontal stress is approximately 10-20°. Nous avons analysé les résultats de mesures de contrainte par surcarottage réalisées sur le site Zedex, du laboratoire souterrain HRL d’Aspö, en suède. Deux types de cellule de mesure ont été utilisés sur ce site : la cellule à 9 jauges (du type CSIR) et la cellule à 12 jauges (du type CSIRO HI). Un programme d’inversion mettant en œuvre une norme par moindres carrés a été développé et validé. Les champs de contrainte primaires et secondaires du site Zedex ont été évalués d’une part en considérant chaque mesure isolément, d’autre part en intégrant l’ensemble des données de déformation dans une inversion unique. Nos résultats suggèrent que l‘association des diverses mesures dans une intégration unique améliore nettement la détermination du champ de contrainte. Un résultat intéressant est le bon accord entre ces nouveaux résultats et les résultats des mesures par fracturation hydraulique. Les écarts sur l’amplitude des contraintes horizontales est de l’ordre de 3 Mpa, les écarts sur les orientations de l’ordre de 10-20°. Auf dem Zedex Test Gelände im Äspö Festgesteinslabor (HRL) wurde eine Spannungsanalyse mittels Overcoring Spannungsmessungen durchgeführt. Hierzu wurden zwei verschiedene Methoden verwendet: das 9-kanal Borre Gerät (CSIR- Ausführung) und die 12-Kanal CSIRO HI Zelle. Inversionsprogramme, die auf dem “least-squares”- Kriterium basieren, wurden entwickelt und kalibriert. Das primäre und sekundäre Spannungsfeld des Zedex Test Geländes wurde sowohl aus Verformungsdaten individueller Zellen als auch aus Kombination beider Zellen ermittelt. Wir nehmen an, daß die Kombination der Messergebnisse beider Geräte die Bestimmung des Spannungsfeldes signifikant verbessert. Überzeugender Beweis hierfür ist die gute Übereinstimmung der überprüften Overcoring Daten und Ergebnisse aus existierenden Hydraulic Fracturing Versuchen. Die Abweichungen der horizontalen Spannungen aus beiden Datensätzen ist etwa 3 MPa und Abweichungen der Orientierung der größten Horizontalspannung liegen bei etwa 10-20°.

Jan 1, 2003

By L. C. IlsLey

A list of permissible mine equipment approved by the Bureau of Mines before January 1, 1940, was published in Bureau of Mines Information Circu- lar 71103. Information Circular 71584, published as a supplement thereto, listed equipment approved during the calendar year 1940. The present list contains the information given in those two circulars, as well as approvals issued during the calendar year 1941. It embraces electrically operated air compressors, coal drills, conveyors and loading machines, electrical equipment for mine fans, mining machines and trucks, mine pumps, rock- dust distributors, room hoists, storage-battery gathering and haulage locomotives, storage-battery power trucks and shuttle cars, mine telephones, junction and distribution boxes, electric cap lamps, flame safety lamps, electric hand and trip lamps, electric flood lamps, flashlights, methane detectors, and single- and multiple-shot blasting units. The equipment listed is not approved by the Bureau of Mines until found by inspection and test to comply with minimum standards of safety as outlined in "schedules" prepared upon the basis of many years of ex- perience in dealing with safety problems confronting the coal-mining in- dustry. The use of such equipment in mines that are known to be gassy,. as well as in those that may become so, is earnestly recommended in the interests of safety. This circular is published so that the industry may be kept informed as to the many types of machines, devices, and lamps that are available for reducing explosion and other hazards incidental to coal mining.

Apr 1, 1942

By B. Amadei, F. Tonon

Rock stress measurement is cast in the more general context of the determination of boundary conditions for rock engineering. A study on the effect of elastic anisotropy on underground excavations reveals that this effect is actually controlled by the imposed boundary conditions. Applications to tunneling and to the Underground Research Laboratory (URL), Canada, exemplify a procedure for boundary condition estimation formerly developed by the authors. The procedure displayed fast convergence despite the complex geometry, and the high degree of non-linearity of the models. In the URL application, the 3-D model was able to completely reproduce the complex measured stress pattern, and the 90° rotation of the principal in situ stresses with depth. In order to reliably estimate the boundary conditions reproducing the current in situ state of stress, response measurements of the rock mass to current disturbances are necessary as input data. La mesure des contraintes in situ tombe dans le domaine général de la détermination des conditions aux limites pour les problèmes de mécanique des roches. Une étude sur le rôle de l’anisotropie élastique sur les excavations souterraines montre que ce rôle est contrôlé par les conditions aux limites qui sont imposées. L’application aux tunnels et au Laboratoire Souterrain de Recherche (URL) au Canada, nous permet de présenter une méthode de détermination des conditions aux limites. La méthode converge rapidement bien que le géométrie soit complexe et que le problème soit non-linéaire. Pour le URL, le modèle 3D est capable de reproduire la distribution des contraintes qui ont été mesurées ainsi que la rotation de 90 degrés des contraintes in situ avec la profondeur. Afin de déterminer avec précision les conditions aux limites responsables pour la distribution actuelle des contraintes, la réponse du massif rocheux doit être connue et mesurée. In der Felsentechnik sind die Spannungsmessungen in Gestein an die Bestimmung der Randbedingungen gebunden. Eine Studie legt dar, dass der Effekt elastischer Anisotropie in unterirdischen Aushoehlungen von den Randbedingungen kontrolliert ist. Eine von den Authoren entwickelte Methode zur Bestimmung der Randbedingungen wird an Beispielen im Tunnelbau und im Underground Research Laboratory (URL) in Kanada illustriert. Auch bei komplexer Geometrie und einem hohen Grad an Nicht-Linearitaet zeigt diese Methode ein schnelles Konvergenzverhalten. Ein 3D-Model und dessen 90° Drehung der lokalen Hauptspannungen mit der Tiefe, kann bei einer URL Anwendung vollstaendig reproduziert werden. Um mit dieser Methode die Randbedingungen zuverlaessig abschaetzen zu koennen, werden der gegenwaertige lokale Spannungszustand sowie die Antwort des Gesteins und die resultierenden Stoerungen als Eingabedaten benoetigt.

Jan 1, 2003

By Zhou Lu-Jian

The Port of Shekou is situated at Shenzhen Bay on the east bank of Lingding Ocean. Its coastline is about 6 km long and the water depth near the shore is Favourable. Across the bay is the ' New Territories " of Hong Kong. The port is at a distance of 22-23 seamilesaway from center of Hong Kong and 80 seamiles to Huangpu Harbour of Guangzhou, its highway links with Shen-Guang Highay. Since 19 79 China Merchants Group of the Transportation Department, began to set up Shekou Industrial Zone, the port has been developing and flouri­shing in business. With 15 large or small berths in all, the present portline is 2600 m, and the annual cargo throughout is over 3,000,000 tons and the annual passenger traffic is about 2,000,000 persons. Equalling a medium-scale seaport, it has been officially approved as an oceangoing transit port by the ministry of Transportation. The construction of Shekou port is chara-terized by the self-collected funds and the short construction period. In view of this, the optional plan of the port structure must serve the requirements of simplicity in struture, economy in mate­rial and speed in construction. That accounts for the most application of the sheet piling type to the port in Shekou. Once the project was approved, the cons­truction started. Only within an average period of 7-8 months, a deep water pier was completed and put into operation, which covered series of processes from exploration, designing, tender for con­struction to completion.

Jan 1, 1991

By James G. McKelvey

Owners have seen several major tunnel projects in recent years fall victim to a general reduction in the number of bidders as well as an erratic range of pricing. It should be noted though that this is not a universal trend and some projects have seen good competitive bids. Contractual terms and conditions are an important factor in attracting good competition. The Front End documents of tunnel projects have come under increasing scrutiny as tunneling contractors in the U.S. industry are looking much more closely at their risk exposure in the contract terms and conditions. Considering the amount of tunnel construction work upcoming in North America, it is important that General and Special Conditions are put together in a way that provides a reasonable basis to execute the Contract and also provide a fair, balanced and swift way to resolve disputes.

Jan 1, 2008

By Ali Porbaha

The use of soil nailing technology as a cost effective alternative for excavation support and slope stabilization has substantially increased in the United States during the last decade. For example, in the past thirteen years, more than 185,800 square meters of soil nail walls have been constructed in California alone. The conventional soil nail systems pose difficulties when ground conditions are subject to caving, for instance for silty sand (sugar sand) or cobbles and boulders. The construction industry has developed self drilling hollow bar systems (or pressure injected bored, IBO) that combine both drilling, placing and grouting in a single operation as a solution to speed up construction. While the system is extensively used for temporary applications, nevertheless, some concerns, particularly about corrosion, has limited the use of this technology as a permanent system in North America. This study presents several issues related to self drilling soil nail systems, the results of a field investigation and a summary of the research project.

Jan 1, 2006

By Adriaan van Seters

"Abstract The content of Eurocode 7 – Part 1 and Part 2 – with respect to piled foundations is outlined. The important role of pile testing is presented and the derivation of the characteristic value of pile bearing resistance is explained. Recommendations for the use of correlation factors are given. The ongoing work of the Evolution Groups on piling is to prepare a revision of Eurocode 7 after 2019. Future topics and changes are highlighted.General outline of pile design by Eurocode 7In his paper for this conference Frank (2014) outlined the various aspects of standardisation for pile foundations, which involves Eurocode 7 as leading for pile construction in Europe. Standards for pile testing and execution of piling works were established in the last 15 years.This paper focuses on the design of piled foundations according to the design code Eurocode 7, which consists of 2 parts:EN 1997-1 Geotechnical design - Part 1: General Rules (CEN, 2004);EN 1997-2 Geotechnical design – Part 2: Ground investigation and testing (CEN, 2007) In Eurocode 7-1, Section 7 – Pile Foundations - deals with the design of piles. The safety concept for pile design is given in Section 2 – Basis of Geotechnical Design - for the three Design Approaches.In Section 7 presents the design of piles according to four methods:1. Results of static load tests2. Empirical or analytical calculation methods3. Results of dynamic load tests4. Observed performance of a comparable pile foundation.Guidelines for the ground investigation for piles is provided in Eurocode 7-2, Annex B.3. In the Annexes of Eurocode 7-2 examples of analytical methods to determine the bearing resistance of a single pile based on the results of various ground investigation techniques are given. Thus calculation models are presented based on design using the results of Cone Penetration Tests (D.6 and D.7) and Pressuremeter Tests (E.3). The Annexes of Eurocode 7-2 are informative.For the interpretation of Eurocode 7, reference is made to Frank et al (2004) and Bond and Harris(2008)."

Jan 1, 2014

By F. R. Lee

When the Bureau of Mines was established in July 1910, one of the problems immediately attacked by the new organization was the development of standard, for the design and testing of electrical equipment that could be used without fear of initiating fires and explosions in underground coal mines. Research and investigation by Bureau personnel, supplemented by the published results of similar work by European mining authorities, led to the establishment of standards or "schedules." which guide manufacturers ill the design of many types of electrically operated machines and devices used in underground coal Mining. By issuing these standards, Bureau personnel establish the requirements to be met by such equipment before it tan be approved by the Bureau of Mines as permissible for use in gassy coal mines. Every 2 years the Bureau of Mines publishes a list of equipment that leas been accepted as approved or permissible during the preceding 2 calendar years. This is done to inform the mining industry of the availability y of the latest equip¬ment for safe use underground.

Jan 1, 1964

By M. D. Dolan

In this study, the development of a new method for investigating the diffusion of metal cations in multi-component slag systems, using microprobe analysis is discussed. This method allows the analysis of the diffusion of multiple species within a single system. This project has focused on the diffusion characteristics of manganese, iron, calcium and silicon in silicate slags, in order to simulate industrial steel and ferromanganese production. The diffusion behaviour of transition metals is of particular interest because of the effects of their variable valence. This study identified the variation in diffusivity of slag components with changes in composition and temperature of multi-component slag systems. The molecular structure of the experimental calcium-aluminosilicate slags was investigated to determine the chemical and physical properties that influence diffusion behaviour. This experimental data was used to develop predictive models for diffusivity. These models enable the estimation of the diffusivity of many slag components in complex slags, over a range of compositions.

Jan 1, 2004

By Kent C. Werle

This brief discusses the installation and application of sleeved piles of two different types for two different projects, the W, Seattle to Harbor Island Swing Bridge Project and the Seattle Access Project. A description of these relatively novel piling systems is given, as well as some notes on their installation and application. As implied by the term "sleeved" these are piles which consist of two piles, an inner pile combined with an outer concentric sleeve pile. Background, Swing Bridge The Swing Bridge project is virtually unique in the world in that it is a "lift and turn" swing bridge. It is also a concrete, cast -in-place segmental bridge which is designed to be moveable.

Jan 1, 1990

By Jiwei Duan

The deformation and load transfer behavior of a single soil-cement column are studied with the finite element method. The results show that there is an effective length for a soil-cement column. Beyond this length, the settlement of the column is approximately equal to a constant. The effective pile length is introduced to the concentric cylinder approach (Randolph and Wroth 1978), and an analytical formula for estimating the settlement of a single flexible pile is presented. A second analytical formula for determining the effective pile length of a soil-cement column is obtained and an example shows that the calculated and measured results are in quite good agreement.

Jan 1, 2002

By R. J. Folic

Investigations of the vibrations of a pile in soil are performed on a dynamic model in the form of a prismatic bar of finite axial and flexural stifnesses with a discrete mass at its free end representing the cap. The soil is represented by a system of springs of constant and variable stiffnesses. Oscillation differential equations are derived by means of the Hamiltonian principle for non-conservative systems. The problem is reduced to a coupled system of two non-linear partial differential equations with corresponding initial-boundary conditions. Frequency equations of longitudinal and lateral linearized equations are formed. The paper determines natural frequenc­ies and oscillation modes. It separately examines longitudinal vibrations excitated by a hermonic force acting upon the pile cap, and lateral vibrations excitated by an impulse acting upon the cap. The results of the numerical processing are presented in respective diagrams in dimensionless form.

Jan 1, 2010

By M. Ng

As part of a long-term study of titanium minerals processing being undertaken by the Julius Kruttschnitt Mineral Research Centre, techniques have been developed to measure the resistivity of ilmenite, rutile, zircon and other associated minerals. The techniques have proven reproducible and have allowed the measurement of resistivity under conditions of varying temperature, surface condition and surface moisture adsorption. The measured values can be linked to the separability of the minerals in the dry plant, and hence are useful as a diagnostic test for existing plants when performance deteriorates, or for greenfield sites to investigate potential problems. One of the major problems in electrical separation of titanium minerals is surface coating on the mineral grains. Coatings can make normally conductive minerals such as ilmenite and leucoxene behave much more like non-conductors. Electrical separation of surface contaminated ilmenite from non-conductors then becomes extremely difficult unless the surface contaminant is first removed. The resistivity measurement technique was used to evaluate the effect of surface cleaning on the resistivity of ilmenite and zircon from a Western Australian deposit which will shortly be in production. Ten different attritioning methods were evaluated, ranging from simple rinsing inwater to chemical attritioning in sulphuric acid combined with ultrasonic leaching. A roasting and quenching step was also investigated. As would be expected, the gentler treatments, such as rinsing in water or Calgon, had only amoderate effect on the ilmenite surface coatings. Ilmenite resistivity decreased by about 1 order of magnitude from 5.6 x108?m to between 2.5 and 4.4 x107?m. More intense treatments had a much more pronounced effect. The most effective, reduced ilmenite resistivity to 6.5 x105?m or three orders of magnitude. Zircon was relatively unaffected by any of the attritioning methods, with only a small increase in resistivity observed from 8.0 x1012?m to 2 x1013 ?m. The results show that measurement of mineral resistivity allows the effect of surface treatments to be easily quantified in a way that has benefits for greenfield site development where only small samples are available for testing. The effect of surface moisture has also been investigated using resistivity measurements. Measurements were made on zircon in an environmental chamber in which both humidity and temperature could be closely controlled. Zircon resistivity at 60 deg C decreased from 6 x1011?m at 5% relative humidity to 8 x108?m at 95% humidity. Moisture content and moisture re-adsorption from dry of zircon and number of other minerals were measured using a Mettler moisture analyser. Zircon adsorbed the least amount of surface moisture (0.05–0.09%) but re-adsorbed moisture from dry the fastest, reaching 98% of the original level in 10 minutes. Leucoxene adsorbed the most moisture (0.67%), but was much slower re-adsorbing this moisture from the dry state, reaching only 63% of the original level in 10 minutes. The difference was attributed to the surface characteristics of the grains, the leucoxene being much more porous than the zircon examined. The resistivities and differing rates of moisture adsorption can be used to quantify the effects of changes in atmospheric conditions of the performance of electrical separation in dry plants.

Jan 1, 2003

By K S. Fisher, J D. Pease

The installation of the George Fisher flowsheet in the lead/zinc concentrator at Mount Isa Mines Limited has recently been completed. The George Fisher flowsheet involved moving flotation capacity from the lead circuit to the zinc circuit and changes in zinc circuitry, changes in the reagent regime and increased regrinding capacity, using IsaMills, to regrind some streams to 80 per cent passing seven microns. The project was highly successful, delivering a five per cent increase in zinc recovery within a fortnight of commissioning. The George Fisher flowsheet was developed over six years. Laboratory work built upon the knowledge gained from investigating and processing the Mount Isa and Hilton orebodies. The engineering design and construction for the brownfield expansion of the existing lead/zinc concentrator had significant involvement from the operational, maintenance and technical personnel. Experienced personnel were seconded from the concentrator to the design and construction groups to ensure smooth integration of the new flowsheet into the existing concentrator with minimum downtime, and maximising the reuse of existing equipment. The combination of thorough design, good project integration with operations, and a good commissioning plan allowed almost immediate delivery of project gains. The project was highly successful, the full design improvements were achieved within two weeks, allowing the focus to move to developing future improvements.

Jan 1, 2000

By A. Fahimifar, H. Soroush

Abstract: In order to develop non-destructive methods in studying physical and mechanical properties of rock and replacing them with difficult and expensive static methods, several ultrasonic tests were carried out on cylindrical rock specimens in accordance with the ISRM suggested methods and velocity of P and S waves were determined. Also, density, porosity, water absorption, uniaxial compressive strength and indirect tensile strength were determined for each specimen in accordance with ISRM suggested methods. According to above tests static and dynamic elastic constants were calculated After statistical analysis of data obtained from tests, the relationships between velocity of elastic waves and physical or mechanical parameters were determined and some equations were obtained. Also similar analyses were performed on static and dynamic constants and some equations were extracted. Using these equations, the physical and mechanical parameters of rock and also static elastic constants can be estimated by conducting simple and quick tests (i.e. ultrasonic tests). Abriß: Um zu entwickeln, die zerstörungsfreien Methoden für Studieren die physischen und mechanischen Eigentümer von Steinen und auch ist für Ersetzen diese Methoden mit schwierigen teuren statischen Methoden, mehrere altrasonic Prüfungen auf zylindrischen Steinproben gemäß ISRM anregenden Methoden und den Geschwindigkeiten von S und P Wellen bestimmt worden sind durchgeführt worden. Außer der Dichtheit und der Porosität betonen Wasser Aufnahme und monoaxial Widerstand und dehnbaren indirekten Widerstand jeder Probe betreffend der erhaltenen Ergebnisse die atmosphärische Aufladung sind bestimmt worden und die dynamischen Faktoren der Steine sind kalkuliert worden. Nachdem statistische Analyse die Korrelation der Ergebnisse zwischen der Geschwindigkeit elastischer Wellen und mechanischer und physischer Eigentümer der Steine erhalten worden ist, und mehrere Verhältnisse sind vorgeschlagen worden. Eine ähnliche Analyse ist auf atmosphärischer Aufladung und dynamischen Faktoren durchgeführt worden und einige Verhältnisse sind erhalten worden. Mit Hilfe dieser Verhältnisse die physischen und mathematischen Eigentümer von Steinen und auch können die Statistik Faktoren durch einfachen und schnellen altrasonic Prüfungen erhalten werden. Resume: Puor le development des method non-destructive et evaluuation des propietes physical et mechanical des rock et superseding avec les methods dificzle et cher statique, c‘ est fait plusieur essayes ultrasonique sur les echantillons cylinrique et par a port le proposale TSRM et le vittesse des ondes P et S et densite et porosite et absorption des eaux le resistant de pression uniaxial et resistance de chaque echantillon est determinee. A la fin en base des resultat obtenue les constant statique et dynamique des roches sont calcule. Apres les analyses statistiquc sur les resultat obtenue du les essaybs, c‘ etait produit les relation entre les viptesse les ondes elastique et les proprietes physic et mechanicue des roches et c est propose quelque relations. Aussi le meme enterpretation sur les constant statique etdinamique. En possezon de ces relations, les spesificatio physique, aussi on peut trouver leur constant statique, avel les essayes sample et raptid a d ultrasonique.

Jan 1, 2003

By R. J. Hundermark, S. Sun

The oxidation state dependence of the electrical conductivity of a calcium ferrite slag with 25 wt% CaO was measured at 1300°C using a shallow slag layer and two-electrode technique. The experiments were started in air and the slag was sequentially reduced by means of a controlled gas atmosphere using CO2and CO. The electrical conductivity in air was approximately 300 S/m and increased with reduction to approximately 1900 S/m at a pO2of 10-10atm. The interest in the oxidation state dependence of the conductivity of calcium ferrite slags was to provide a comparison with the conductivity of iron silicate slags and to establish the effect of slag basicity on the electrical conductivity and its oxidation state dependence. The results obtained are discussed in terms of the slag structural information available in the literature. The co-ordination of the ferric ions appears to play a large role in determining the electrical conductivity. Keywords: calcium ferrite, slags, electrical conductivity.

Jan 1, 2004

By Robert Harris, David Duncan

The Samira Hill gold mine represents the first commercial gold project for the landlocked country of Niger in West Africa. It began production in October 2004 as the result of over 10 years of exploration and development work. There were several administrative, social and technical challenges that had to be overcome to realize the successful development of the project. The Samira mine is located on the geological structure known as the ‘Samira Horizon’ which is developing as a promising district for additional discoveries and other mine developments.

Jan 1, 2005

There are available today many various types of mixing systems, tank types and process liquors confronting the process designer of gold adsorption circuits. This short paper is to give the process designer an insight into the special mixing requirements for resin-in-leach and resin-in-pulp, plus the advantages and disadvantages of the various mixing systems that are available to agitate the required tank shapes. An understanding of the latest developments in this important process area of gold production is addressed and information given on the results of resin degradation in various tank sizes over long periods of mechanical agitation.

Jan 1, 2007

Mineral sand beneficiation plants comprise a complex combination of electrostatic, magnetic and gravity based separation techniques. These are combined and replicated in ways that provide the most efficient and cost effective separation of the valuable components. On line instrumentation has been developed at the JKMRC (eg. conductor/non-conductor(CNC) ) to measure the properties of the dry plant process streams. This paper provides results from the recent development of a novel low cost mass flow meter and discusses their combined use with the CNC instrumentation for the control of dry separation circuits.

Jan 1, 2003