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By G. S. Camm

Gwynfynydd is a small, high-grade black shale-hosted vein-gold deposit. The Chidlaw Link Zone is the only area being mined and contains 24 000 t ore grading 15.2 g/t gold. Within the Link Zone a complex vein structure occurs consisting of a mother vein up to 5 m thick and narrow (less than 0.5 m) leader veins. The former shows minor variations in dip, strike and thickness, whereas the latter show marked changes in all three. The leader veins are hosted within the footwall zone of the mother vein and both are composed of quartz with galena, sphalerite, chalcopyrite, pyrite and minor arsenopyrite. The vein system is transected by a series of cross-vein and intra-vein dip-slip faults. Pockets of gold occur at vein intersections or branches and within the complex footwall zone and are often related to variations in vein attitude and/or geometry. The Chidlaw Link Zone displays a complex, erratic distribution of gold mineralisation and a multi-stage history of structural activity, fluid flow and mineral deposition

Jun 18, 1905

By Z. W. Nkosi, M. Sephton, J. H. Potgieter

The exhaust system is a complex assembly of various components performing important tasks in harsh environments. Carbon steels have been used extensively in exhaust systems, but pressure for lower cost, increased fuel efficiency; lower hazardous emissions, weight savings and increased life expectancy have shifted the emphasis to stainless steels. In response to the growing consumption of stainless steels in automotive exhaust systems, the need to properly evaluate their corrosion resistance properties in order to ensure their appropriate use, has increased substantially. This paper evaluated the most common corrosion and oxidation tests developed that are used and applied it to four common stainless steels often employed in hot end exhaust components. In a summary considering the weight loss of an alloy, it general corrosion rate and pitting resistance under all the test conditions for hot end exhaust components, results indicate that 434 was by far the most corrosion resistant alloy, followed by 1.4509 and 321, and lastly 304 was the least corrosion resistant. In general, the ferritic stainless steels, especially 434, outperformed the austenitic ones under all the test conditions.

Jan 1, 2006

By S. Klein, D. Crouthamel, D. W. Farmer, S. H. Phillips

Groundwater inflows during construction pose one of the greatest risks to the successful completion of tunnel projects. Inflows can result in safety concerns, difficulty in mining and ground support, impact sensitive environmental habitats, create surface settlement and increase costs. Adequately planned pre-excavation grouting programs benefit both the Owner and Contractor in reducing risks and controlling project costs and potential schedule delays. This paper outlines strategic guidelines for assessment of site conditions for pre-excavation grouting hard rock tunnels. It also describes the design of pre-excavation grouting programs with respect to project requirements.

Jan 1, 2005

Close spatial relationships between the deposits of the Etheridge Goldfield (23 000 kg of bullion) and various regional geological and geophysical features suggest that genesis of the ore deposits was a multi-stage process that started with magmatic and metamorphic stages in the mid-Proterozoic, climaxed with structural and hydrothermal stages in the late Palaeozoic and terminated with an oxidation enrichment stage in the Cainozoic. Acceptance of this hypothesis permits classification of the Georgetown region into areas likely to contain deposits of the Etheridge type and those unlikely to do so. Consequently there is little scope for the discovery of extensions of this field. However, the stratigraphic interval between the source rocks of the Etheridge field and stratigraphically bigger host rocks of the Croydon field may contain disseminated replacement gold deposits of the Carlin type. The potential host (pyritic carbonaceous and locally dolomitic siltstone of the Candlow Formation) is locally faulted and cut by granitoids and the extension of a mineralised, long-standing zone of structural weakness.

Jan 1, 1980

By A. V. Z. Brink

Rock engineering risk is defined in this paper as a function of the potential ground motion; the vulnerability of the workplace; exposure of people; and a general term – quality of information. The paper describes the development of prototype software that is a combination between an expert system approach for determining overall risk assessment, a risk control recommendation and a basic GIS (Graphic Information System) approach for graphically overlying input parameters and the output risk. The expert system uses a Bayesian probabilistic approach to combine various workplace-related information, a quantified seismological environment and the exposure of underground staff to provide an overall RE risk rating. The risk assessment is dynamic in that it is recalculated each time that any of the input parameters change, for example each time a seismic event is recorded in the area of interest. The code was tested on a data set from Savuka Gold. As risk assessment is not an absolute prediction of a specific outcome, it is therefore not possible to relate to individual case studies and the reliability of this method would only be determined after an extensive period of use with appropiate back-analysis. Le risque dans le génie minier est défini dans cette étude comme une fonction du mouvement potentiel de terrain ; la vulnérabilité du lieu de travail ; l’exposition des personnes ; et un terme général – la qualité de l’information. L’étude présente décrit le développement d’un logiciel prototype qui est une combinaison entre une démarche de système expert pour déterminer une évaluation générale du risque, une recommandation pour le contrôle du risque, et une démarche de SIG (Système d’Information Géographique) pour superposer graphiquement les paramètres d’entrée et le risque de sortie. Le système expert utilise une méthode de probabilité bayésienne pour combiner des informations variées sur le lieu de travail, des données quantifiées sur l’environnement sismique, et l’exposition du personnel travaillant sous terre, pour finalement produire un classement général de risque minier (RE). L’évaluation du risque est dynamique en ce sens qu’elle est recalculée à chaque fois qu’un des paramètres d’entrée change, par exemple à chaque fois qu’un évènement sismique est enregistré dans la région. Le code fut testé sur un ensemble de données obtenues de Savuka Gold. Comme l’évaluation du risque ne constitue pas une prédiction absolue d’un résultat spécifique, elle est par conséquent difficile à rattacher à des cas individuels et la validité de cette méthode ne pourrait être déterminée qu’après une longue période d’utilisation avec analyse rétrospective appropriée. Das Gesteinstechnikrisiko wird in dieser Arbeit als Funktion einer möglichen Bodenbewegung definiert; die Anfaälligkeit des Arbeitsplatzes; das Ausgesetztsein der Belegschaft; und ein genreller Begriff - Qualität der Informationen. Das Papier beschreibt die Entwicklung einer Prototyp-Software, die eine Kombination zwischen einem Expertensystemzugang für die Bestimmung der gesamten Risikobeurteilung ist, eine Empfehlung zur Risikokontrolle und eines fundamentalen GIS (graphisches Informationssystem) Zuganges für graphisch darüberliegende Eingangsparameter und das Outputrisiko. Das Expertensystem verwendet eine bayesische Wahrscheinlichkeitsannäherung, um verschiedene mit dem Arbeitsplatz in Verbindung stehende Informationen, ein quantitativ bestimmtes seismologisches Umfeld und das Ausgesetztsein des Untertag-Personals zu kombinieren, um eine gesamte RE-Risikobewertung zur Verfügung zu stellen. Die Risikobeurteilung ist insoferne dynamisch,daß sie stets nachkalkuliert wird wenn sich irgendeiner der Eingangsparameter ändert, z.B. jedesmal wenn ein seismischer Fall im Interessensbereich aufgezeichnet wird. Der Code wurde auf einem Datenbestand von Savuka Gold geprüft. Da die Risikobeurteilung nicht eine absolute Vorhersage eines spezifischen Resultates ist, es ist folglich nicht möglich, sich auf einzelne Fallstudien zu beziehen und die Zuverlässigkeit dieser Methode könnte nur nach einer umfangreichen Benutzungsdauer mit geeigneter Postanalyse bestimmt werden.

Jan 1, 2003

By G. E. Perry, R. D. Seba

The steam soak process is the most widely applied and most successful thermal supplemental recovery process in use today. This process, which consists of injection of steam in various quantities into a well that is subsequently used as a producer, can be repeatedly applied to the same well. The treatment, if successful, will increase the production rate of the well for a given period. For this reason, the steam soak process should be considered primarily as an acceleration method rather than as a method for producing oil that could not be recovered by primary means. However, application of this process to reservoirs containing viscous crude may produce oil that otherwise would have zero present value or would be produced at such low rates by primary methods that it would not be profitable. A major necessity for the successful application of the steam soak process is a source of natural energy. This source of energy may exist in one or more of the following forms: expansion of fluids, compaction, gravity drainage. This study was undertaken to determine the effect of gravity drainage on steam soak production and recovery and to develop a method for predicting production rates, ultimate recovery, and heat requirements when applying this process to a reservoir in which the primary driving mechanism is gravity drainage. (For additional discussion of some of the factors that affect recovery of viscous oils by the steam soak process, see Ref. 5.) Model The model developed for analyzing the performance of the steam soak process in gravity drainage reservoirs is a modified form of that developed by Matthews and Lefkovits.1,2 The model used in this study consists of two concentric cylindrical volumes of productive formation with cap and base rock of impermeable material. The inner cylinder, extending from the radius of the wellbore to some predetermined radius, is referred to as the hot zone; and the outer cylinder extending from the exterior boundary of the hot zone to the outer drainage boundary will be referred to as the partially heated zone. Fig. 1 is a schematic cross-section of the model, indicating its thermal properties. Horizontally the reservoir is divided into two regions, the upper region having a high gas saturation and residual liquid saturation, and the lower region containing a high liquid saturation. The boundary between these two regions is referred to as the free surface, which drops and changes shape as fluid is produced from the reservoir. The model was used to analyze the steam soak process by applying the following assumptions: 1. The horizontal formation is composed of one or more homogeneous noninterconnected layers containing incompressible fluids. Each layer is treated separately. 2. The hot zone is heated by the initial soak and is maintained at the steam temperature corresponding to atmospheric pressure by resoaking. 3. The height of the free surface at the producing well is at all times zero (producing well is pumped off). 4. The position of the free surface at the start of

Jan 1, 1970

By Casey Erickson

Goldstrike Property ??Located in Elko, NV USA?Carlin Trend ??Mining Since 1985 ??27 Million Ounces of Gold Mined ??Production of 400,000 tons/day ??1,600 Employees

May 1, 2011

By K. Meyer

"The largest cost centres of the David Bell Mine concentrator are grinding, leaching and effluent treatment. Optimizing results during the 6th year of operation are listed below: o SAG mill slurry density control and operating strategies improved liner life and media consumption by 10 and 25%, respectively.o Poly-met liners clad the SAG mill except for the feed end. Lower noise levels and reduced mill downtime have resulted in an improved and more efficient workplace (time required for liner changes is 2 to 3%).o A comparative grinding media study using seven different marked media at the same time showed media wear rates range 120 to 198 mg/kWh and ball mill charge replacement frequencies of 8.3 to 13.1 per year, and that a meaningful wear test must include all media to be tested at the same time in the same mill. High quality carbon steel cylinders had the best economics.o Pre-aeration, using pure gaseous oxygen is accomplished in pipe reactors. Small bubble generators provide oxygen in the first three leach tanks. 1500 to 3000 kg of oxygen is consumed per day. Leach kinetics have improved and trends indicate increases in gold recovery of three to seven ounces per day at reduced costs. Effects of reduced cyanidation of accessory metals on the effluent treatment plant will be discussed in a separate paper."

Jan 1, 1991

By L. B. Berger

The Haldane gas-analysis apparatus used by the Bureau of Mines is patterned after the device developed by Haldane 4/ and differs from it only in structural modifications that have been added to facilitate operation and simplify construction. The apparatus was developed to permit determination of carbon dioxide, combustible gases, and oxygen with a degree of accuracy not attainable with apparatus of the types ordinarily used for the analysis of fuel gases, flue gases, and similar mixtures. The Haldane apparatus is used by the Bureau of Mines chiefly in the analysis of air samples collected in coal and metal mines and other underground workings and is applied also in the analysis of many other types of gas mixtures when accurate determination of certain constituents is desired.

Jan 1, 1938

By N. McEwan

Keywords: refractories, chromite, Marico This paper examines the role of refractory-grade chromite in refractories. The chromite deposit at Verref?s Marico Chrome mine is described. The refractory properties of chromite and their role in basic refractories are described. The properties and metallurgical applications of chrome-containing refractories are described and finally environmental issues associated with chrome-containing refractories are discussed.

Jan 1, 2011

By K. G. Tshilombo

It should be possible to use an oxygen probe to follow iron removal during converting, if local equilibrium is established between iron in the matte and the iron oxides in the fayalitic slag. The oxygen activity is expected to increase strongly as the iron content of the matte decreases (and the iron activity in the matte drops) while the iron oxide activity in the slag remains constant. To test this idea, oxygen activities were measured in synthetic mattes (made up of mixtures of Cu2S, FeS and Ni3S2) when in contact with silica saturated SiO2-FeO slags, and silica and (initially) magnetite saturated SiO2-FeO-Fe3O4slags. The measurements were performed on laboratory scale at 1250°C, using an oxygen probe consisting of an MgO-stabilized zirconia electrolyte and Fe/FeO reference, and containing the sample in a silica crucible. Electrical contact to the matte was by means of a platinum wire. The measured oxygen activity was sensitive to the iron content of the matte, and insensitive to the composition of the gas atmosphere over the melt. The measured oxygen activity was generally close to that predicted by Fact Sage calculations. This indicates that such oxygen activity measurements could be useful to monitor iron removal during converting of nickel-copper-iron mattes.

Jan 1, 2007

By G J. Corbett, P Magner, M McKenzie

Structures formed during ductile deformation have been reactivated during the later brittle mineralisation process. Two generations of folding are classified as: early recumbent megascopic FI folds and FI shears which transpose the hinge regions, and later upright F2 folds. S1 is folded about F2 folds which contain axial planar S2 crenulation cleavage. Vergence relationships between S1 and bedding indicate that many of the mineralised structures occupy sites of FI folds which have acted as plumbing systems for later gold mineralisation (eg Blackwater mine). The Globe-Progress gold mineralisation is localised by a major jog formed by sinistral strike-slip movement on two FI fault segments and mineralisation also occurs in smaller jogs along strike (eg Sir Francis Drake, Happy Valley-Merrijigs, Cumberland).   The lodes of ribbon quartz which exploit the FI shears and local bedding planes, are inferred to have mostly formed after the peak of metamorphism, possibly related to the emplacement of Carboniferous granites. This was followed by a sequence of vein deposition and wallrock alteration which consists of quartz-As/Fe sulphides ? carbonate - stibnite ¦ trace base metal sulphides and Bi-sulphosalts ? illitic clay/sericite-chlorite. Gold at Globe-Progress is mainly encapsulated in arsenopyrite. At Blackwater, free high fineness gold occurs in partings in lode quartz with late sericite-chlorite. The above sequence of events is comparable to that encountered in many intrusion-related gold systems throughout the Southwest Pacific region. There is a spatial relationship between gold mineralisation and dykes variably described as diabase, dolerite or lamprophyre. Alkaline rocks occur in many Pacific rim and older goldfields and may possibly be related to a magmatic source for gold mineralisation.

Jan 1, 1997

By J. N. Van der Merwe

The paper provides an overview of subsidence research which was done by the Sasol Company in South Africa over a period of more than six years. The magnitudes of subsidence elements in South Africa are largely similar to those in the U.S.A. and Australia, as opposed to Europe. The research resulted in a subsidence prediction method with a new approach to the prediction of ground strain. The paper also describes the effects of subsidence on various commonly occurring surface structures such as roads, overland conveyor belts, pipe lines and power pylons. It is concluded that while most structures are not specifically designed to accommodate mining induced displacements, they can nontheless be undermined safely and economically with only minor precautions.

Jan 1, 1986

This Department handles all ores prior to blast-furnacing, the object of the operations being to mix the lead-bearing material with fiuxes, eliminate sulphur from the mixture, and produce a homogeneous sintered product which is chemically and physically suitable for treatment in the blast furnaces.During the financial year ended the 30th June, 1937, the tonnage of charge treated was 458,960 tons, containing some 183,470 tons of lead and 8,504,000 oz. of silver.The quantities of the principal components of the charge treated were as follow:-

Jan 1, 1937

By Guy Chevalier, Jean-Guy Chartrand, Louis Barrette, Daniel Michaud, Michel Fortin

"COREM has developed, specifically for the mineral industry, a mobile laboratory using the Laser-Induced Breakdown Spectroscopy (LIBS) technique. It has been used to perform onstream analysis (OSA) of the chemical composition of slurries in both gold-ore and iron-ore processing plants. Industrial tests have been carried out respectively at La Mine Doyon (Cambior), a gold-ore processing plant near Rouyn-Noranda, Quebec, and at QCM's iron-ore pelletizing plant in Port-Cartier, Quebec. The aim was to demonstrate that the LIBS technique is capable of providing information that meets the needs for process control. C, Si, Ca, Mg, Mn and Al were the elements targeted on iron ore while Cu, Fe, Ag and Au were targeted for gold ore. The results obtained meet or exceed the requirements for process control and consequently clearly show that the LIBS technique is suitable for industrial applications.The feasibility of OSA, through in-plant validations using COREM’s LIBS mobile laboratory, has been demonstrated in four essential aspects: slurry sampling, LIBS chemical measurement, robustness for continuous operation, and functionality for industrial operators.INTRODUCTIONThere is a general need for optimization in the mineral industry. Process control is a favoured means to achieve this goal (McKee 1991). Real-time knowledge of process status is the key to effective control (Da Silva 1994). Only a few techniques, such as XRF, NMR and digital imaging, are currently amenable to chemically monitor industrial processes (Braden 2002). LIBS is an emerging technique with appealing characteristics for on-line and real-time measurement of bulk material (Lorenzen 1992, Palanco 2000). While our ultimate goal is to provide our industrial partners with performing monitoring tools, a shorter-viewed objective is to demonstrate the feasibility of developing a LIBS system for OSA. The LIBS technique has shown interesting capabilities for measuring solids, liquids, dusts and gases. Our work has focused on mineral slurries (Barrette 1999 and 2001, Turmel 1999). Special equipment is needed to perform in-plant validations. A mobile laboratory based on the LIBS technology has been assembled for this task."

Jan 1, 2004

WHILE in the employ of the Broken Hill Associated Smelters and the Electrolytic Zinc Oompanies at their South Melbourne Research Station, the writer was detailed to investigate the principles underlying the Parkes Process with a view of determining:1. The Interdependence of the variables:(a) Quantity of zinc required per charge,(b) Temperature of stirring of each zincing,(c) Silver content of the bullion after first zinculg,(d) Silver content of the bullion after second zincing,(e) Silver grade of the crusts produced for retorting, with reference to the method of working the Parkes Process then in operation at Port Pirie.2. The possibility of effecting improvements in the Port Pirie practice of desilverising, especially with respect to:(a) Silver grade of the crusts produced for retorting.(b) Quantity of zinc required per charge.The method of desilverising in practice at Port Pirie was a two-stage zincing.In both zincings the bullion was cooled to its solidification temperature and the silver crusts which separated from the lead were completely removed.The crusts from the first zincing were retorted, and the crusts from the second zincing were returned to the first zincing of the next charge.

Jan 1, 1925

By Mary L. Pearson

Ibis report summarizes the results of the contract. Included are summaries of existing legislation pertaining to outcrop barriers and a state-of-the-art survey of outcrop barrier designs and related, mine closure techniques. Six sites were inspected in the field and are presented as case histories The data analysis presented includes a computer modeled seepage analysis, an overburden blew-out analysis, and a wedge stability analysis. The results tit these analyses are interpreted to form recommendations for coal outcrop barriers which will minimize seepage and the potential for failure. Supplementary support and reinforcement alternatives are also discussed.

Jan 1, 1981

By Flavio Begazo Mamani

Recientemente Southern Perú desarrolló un nuevo proyecto donde se modernizaba la planta de Fundicion y se reemplazaba el convencional horno reverbero por la tecnología del ISASMELT, capturando más del 92% de los gases generados durante el proceso de fusión de los concentrados de cobre. En ese sentido, el presente texto describo los efectos de la modernización de la Fundición sobre la calidad anódica. Antes de la modernización de la Fundición, los ánodos fueron producidos en la planta de ánodos ubicada en la Refinería de Cobre de Ilo. Ahora los ánodos son producidos directamente en la Fundición y como resultado, la composición química de los ánodos ha cambiado, principalmente en el contenido de bismuto, antimonio, plomo y zinc, siendo diferentes a los parámetros de diseño original de la Refinería. Asimismo, este factor impulsó a revisar el proceso de remoción de impurezas y los parámetros de la refinación electrolítica en la Refinería para evitar la contaminación del cobre refinado, logrando mantener la continuidad de la producción de cátodos de cobre de alta calidad superando los estándares interna-cionales de la norma ASTM-B115.

Sep 12, 2011

By Betty L. Gibbs

Geologically simple deposits can be modeled quickly and easily with inexpensive gridding and mapping software. Hundreds of mines around the world use RockWorks99 and Surfer 7 for generating contour maps, producing log plots and cross sections, and performing other useful geological calculations. These programs are used by many mining operations as their only modeling and graphical software or they are used in conjunction with larger systems. The investment in learning time is low and the programs produce reasonable quality results with standard computing equipment. RockWorks99 and Surfer 7 provide a good level of capability while maintaining high quality technical integrity. Both programs are used for many applications in mining, oil and gas, environmental and other fields that require analysis of spatial data.

Jan 1, 2000

The Black Hills Mineral Atlas briefly summarizes all important data available on the mines and mineral deposits in the Black Hills that have been explored, developed, mined, or located. The purpose of the atlas is threefold; First, from available data the general potentialities of the Black Hills region can be determined, although it is not possible to calculate actual ore reserves; second, it will provide the necessary basic information regarding a given property or commodity for further detailed study; and third, the compilation is a comprehensive directory of Black Hills deposits.

Jan 1, 1955