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By Román Tejada R

El presente trabajo señala los resultados del sostenimiento de labores subterráneas a través del proceso de pre-inyecciones e inyecciones de contacto y consolidación. De acuerdo a este estudio, se encontró que la mina San Vicente contiene estructuras denominadas "Brechas de Colapso", compuestas de material suelto y deleznable que originan un problema en el laboreo minero. En este sentido, se busca un método que se adecúe a estas estructuras como el "Inyección de cemento"donde no se requiere de muchos aditivos.

Nov 8, 1984

By Julver Álvarez

El presente trabajo describe el comportamiento estructural y mineralización del estaño-cobre en la mina San Rafael, Puno. En este sentido, las pizarras de la formación Sandia del Ordovisco Superior, por metamorfismo de contacto con el intrusivo, han sido transformadas a hornfels, que junto a las cuarcitas se presentan algunas veces como una cubierta superficial sobre el intrusivo. Asimismo, los intrusivos y las pizarras son favorables para la mineralización de estaño, aunque los cuerpos del mineral son más definidos y persistentes en el intrusivo.

Sep 13, 2001

By Yuanbo Zhang, Yongbin Yang, Guanghui Li, Zhengwei Yu, Yufeng Guo, Tao Jiang, Xiaohui Fan, Youming Hu

"Composite agglomeration process (CAP), as an innovative method for preparing blast furnace burden, was developed and has been put into operation in China. CAP is different from traditional agglomeration processes of iron-bearing materials involving sintering and pelletizing. Compared to the traditional agglomeration processes, CAP is characterized by several strengths such as permission of diverse iron-bearing materials in production, obvious improvement of permeability in the feed bed, decreasing the fuel consumption and remarkably increasing the productivity of sintering machine. Furthermore, the use of the composite agglomerates prepared with CAP is capable of obviating the negative effects caused by the differences in quality of sinter and pellets on the operation of blast furnaces. This paper mainly presents an overview of the principle and applications of CAP.Development Background and Principle of CAPhe traditional agglomeration processes including sintering and pelletizing have been the two predominant methods for preparing ironmaking burden from iron-bearing materials. Sintering is a way for agglomeration by heating the coarser fine ores (general granularity 0~10mm). The mechanical strength of irregular porous sinter is obtained by the solidification of molten phase at high temperature process. It has been shown that the production of high basicity sinter (R=1.8~2.2) is characterized by low energy consumption and high efficiency compared to low basicity sintering. Meantime, the finished high basicity sinter is characterized by good mechanical strength and metallurgical performance. Pelletizing is another way for agglomeration by firing wet green pellets, which are balled from the fine grained iron ores or concentrates. Based on the differences of chemical compositions, the finished pellets can be divided into acidic oxidized pellets, fluxed pellets, magnesium-bearing pellets, and so on. The acidic oxidized pellets are the dominant products of modern pelletizing."

Jan 1, 2012

By Marion Dattilo

The search for an improved anode for the electrowinning of lead from fluosi1icic acid medium has led the U.S. Bureau of Mines to investigate composites. Polymer bonded metal oxide powders which may contain catalyst additions were prepared by pressing. These composites display an improved activity toward the oxygen evolution reaction over electrodeposited lead dioxide on titanium, carbon, and nickel substrates. These composite electrodes contain 5 to 10 wt. " binding polymer, with the balance being metal oxides. Lowered anodic potentials achieved using the compnsite anodes resulted in lower levels of lead dioxide deposition during electrowinning.

Jan 1, 1995

By Dirce H. Jacomo, Jaciele G. Teixeira, Anibal Y. Abreu Castillo, EsperidianaA. B. Moura, Yalquiria A. Silva, Rene R. Oliveira, Michelle G. Gomes

"Composites consisting of poly(vinyl alcohol), starch and sugarcane bagasse ashes, using glycerol as plasticizer agent, were prepared by solution casting method. Composites prepared were subjected to electron-beam radiation treatments, at radiation dose of 50 and 80 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The composite samples obtained were evaluated for their water absorption, mechanical and morphological properties.1. IntroductionThe potential of biodegradable polymers and more specifically of biocomposites obtained from agro-resources have long been well established [1-3]. Starch, derivate from variety of botanical sources (cereals, legumes, and tubers) is widely available raw material and one of the most studied and promising agro-resources for the production of biodegradable polymers as matrices for biocomposite applications. However, starch itself is very brittle, hydrophilic and its mechanical properties are very poor for many applications [3 - 5]. The blending of starch with conventional polymers is a promising approach to improve its drawbacks. Recently, many efforts have been made to blend starch with biodegradable synthetic polymers [5, 6]. Polyvinyl alcohol (PYA) is a particularly well-suited synthetic polymer for the formulation of blends with natural polymers, as it is highly polar and can also be manipulated in water solutions, and depending upon its grade, in functional organic solvents as well [3, 7]. PY A has been reported to be an option to blend with starch. Most of the starch/PY A composites have been prepared by casting. However, it is well known that starch/PY A composites has poor in water resistance and mechanical properties after absorbing water [3,8]. Attempts to improve the mechanical properties and to decrease the water absorption property of the starch/PY A composites are made by adding the cross-linkers and plasticizers. Park et al. prepared starch/PY A/citric acid films by the casting method. They also studied the effect of (spell out) citric acid on the mechanical properties and water resistance of composites [9]. Zhai et al. prepared the starch/PY A hydrogels using electron-beam radiation [10]. Different kinds of lignocellulosic fibers have been investigated in blends for formulation of biocomposites."

Jan 1, 2013

By John V. Simmons, Peter J. Simpson

Excavated slopes in open pit coal mines are designed to be as steep as possible consistent with stability and safety requirements. Slope failures occur for many reasons, including oversteepening. This paper is concerned with slope design and excavation experience in the Bowen Basin coalfields of central Queensland (Figure 1), [ ]

Jan 1, 2006

By J. V. Simmons

Composite rock mass failures involve intact rock material as well as fracture and shear on existing defects. Experiences from open-cut coalmining in the Bowen Basin of central Queensland are that failures of this nature occur suddenly with little warning, and are much more common than classical structurally controlled failures. Geological conditions and mining practices in the Bowen Basin are described. The circumstances of a sample of composite failures are described in detail in the paper. From this experience it appears that several aspects of conventional geotechnical investigation and design practice have not contributed significantly to either predicting or controlling the risks associated with sudden failures. These practices are described as myths for reasons outlined in the paper. On the other hand, the reality seems to be that high initial stresses and stress changes caused by excavation lead by a process of extensional deformation to a critical stress condition within the rock mass, and that sudden collapse follows when that critical stress condition can no longer be sustained. It is concluded that learnings gained from underground excavations in rock may be more applicable to open pit excavations than previously thought, and that the processes of prefailure deformation require more careful study if we are to develop more reliable risk management controls.

Jan 1, 2006

By H. S. Radhakrishna

Foundations supporting power transmission and communications towers are subjected to both compression and uplift loads, often of a cyclic nature. Some novel foundations, combining the beneficial features of grouted and helix anchors with that of compression piles and grillages, were developed by Ontario Hydro during the construction of high voltage transmission lines in Ontario, Canada. In addition to meeting the load requirements, the foundations permit easy installation in swampy areas and also minimize impact on environmentally sensitive terrain. This paper describes the features of these composite foundations and outlines the performance criteria used for their design and installation on the basis of load test results.

Jan 1, 2010

By Robert H. Scott

Developments during the past few years have brought coal-based composite fuels to commercial readiness. During the next few years, composite fuels will become available from a number of suppliers. Potential users must evaluate the combustion properties of these fuels to determine equipment and operating changes required for their use. Most work to date has been done with boiler applications. However, many potential non-boiler applications exist in the metals and minerals industry. These applications require specific evaluations appropriate for the processes involved.

Jan 1, 1982

By N. Depountis, Th. Rondoyanni, N. Sabtakakis, K. Kavoura, G. Tsiambaos

"Some typical landslide phenomena in Western Greece, in terms of the geological composition and structure of the affected materials, induced by heavy rainfalls are thoroughly studied and analyzed. The studied cases involved composite landslides on Flysch and Neogene weak rock materials that constitute the most critical landslide prone geological formations in Greece. The studied cases named Platanos, Platanitis and Karya include representative landslide sites as regards to the geological composition and structure of the displaced formations. Thus: (a) flysch formation includes different lithological units as shales, marls, siltstones, sandstones and conglomerates and is closely related to the Alpine orogenesis, suffering intense past tectonic movements and (b) the Plio-Pleistocene sediments include clayey marls, marlstones and siltstones. The investigated landslides , affecting mainly transportation routes, are closely related to heavy rainfalls induced by extreme meteorological events and are controlled by active fault tectonics. Long term movement monitoring using borehole inclinometers and surface benchmarks showed that landslides control was effective only when the proper stabilization measures were taken.INTRODUCTIONLandslides represent a major threat to human life, property, infrastructure and natural environment in most regions of the world. They are recognized by the scientific and politic authorities as having a major socio-economic impact and they represent a significant hazard for the population and the properties in particular locations. Landslide hazard expressed as the probability of occurrence within a reference time period and is a function of the spatial and temporal probability (Varnes, 1984; Guzzetti et al. 1999; Lee and Jones, 2004). The spatial probability of landslide initiation (susceptibility) is mainly related to static causal factors (slope inclination, material properties, etc.), while temporal probability is mainly related to dynamic causal factors such as rain input, increased groundwater levels and drainage, earthquakes, etc. (Van Westen et al. 2005)."

Jan 1, 2015

By R. C. Freas

Composite materials are finding new applications daily, ranging from automotive parts to synthetic lumber. The variety of applications seems almost limitless. However, these emerging products bring both new opportunities and new challenges to the field of industrial minerals. One of the primary challenges is from alternative materials other than industrial minerals. Thus the question is asked whether industrial minerals will truly benefit from the growth in market applications for composite plastics. This article highlights some of the opportunities for industrial minerals while focusing on performance and competitive demands on mineral products intended for use in this developing market.

Jan 1, 2000

By Eugene Sun, Qiang Xu

This presentation will review current applications of composite materials in aircraft design and discuss the challenges involved in maximizing the potential of the composites in aircraft applications.

Jan 1, 2010

By Girish Roy, Robert Goodfellow, Angel Del Amo, Bingzhi Yang

Designing and constructing tunnels in seismic prone areas present unique challenges to both designers and contractors. The Westside Purple Line Extension Project– Section 3 in Los Angeles requires crossing an active fault that may subject the tunnels to extreme structural demands. In order to ensure that the linings will safely accommodate the fault movement, a revolutionary composite section—steel plate embedded in the intrados of the precast concrete segmental tunnel lining was finally selected. Additionally, continuous expansion steel plates over the circumferential joints will be installed to mitigate the potential opening of the circumferential joints.

Jun 13, 2021

By U Briem, R Verreet

The level of wire rope technology used in mine hoisting applications has a significant effect on the overall efficiency of the hoisting system. This paper discusses the effect that a reduction in rope mass per unit length and an increase in rope breaking strength can have on rock skip capacity and hence mine shaft output. A 20 per cent reduction in rope mass per metre for a typical 48 mm hoisting rope, while maintaining the breaking strength, increases the skipÆs capacity by circa 30 per cent at a suspended rope length of 3000 m. Such gains in shaft output, without any significant changes to the shaft or winder design, can have major implications for the feasibility of future deep mine projects. The technical challenge for rope manufacturers is how to get rid of 20 to 30 per cent of the rope mass while keeping the breaking strength and modulus of elasticity of the whole rope constant. CASAR are currently developing steel wire rope constructions where the steel IWRC has been replaced with high strength, high modulus fibres such as Kevlar«, Spectra« and Dyneema«. One of the key aspects of such composite rope designs is to ensure equal load sharing between the different rope components, ie in proportion to their area. If there is a significant difference in modulus between the fibre core and the steel outer strands, the core may not carry its proper proportion of the load and the outer strands would be overloaded. Some technical aspects of the design of composite steel wire ropes are discussed. A design and operational issue that needs careful consideration is the safe non destructive testing (NDT) of composite ropes. Traditional magnetic NDT would only be capable of inspecting the steel wires. Techniques therefore need to be developed that would give operators a reliable indication of the condition of the load bearing fibre core. This paper also discusses possible solutions to this very important NDT question.

Jan 1, 2005

By Norman TE

The design of composite materials for wear resistant service aims at com- bining two or more materials in such a way as to achieve unique and useful properties not generally available in any single homogeneous material. Properties and applications are presented of what might be described as a new generation of wear resistant materials, namely, metallic and part- metallic composites suitable for use in the high abrasion/moderate impact environment encountered in the crushing and screening of ore. Significant cost performance benefit can result from the use of such materials and several specific case histories are discussed. Some promising new developments, utilis- inn white iron and rubber, as yet in the field testing stage, are reviewed. Further comments are offered foreshadow- ing new composite developments, as yet untried but which appear to h,uve merit.

Jan 1, 1978

By L. W. Palmer

Compositing or regularization of drillhole data is common practice in mineral resource estimation and is deemed a necessary step in producing unbiased estimates of mineral resources and reserves. Commonly, data are collected over irregular distances due to the varying relative thicknesses of lithologies drilled or sampling/assaying strategies. This necessitates data transformation to regular lengths of equal size to ensure that all data have the same sample support. However, there have been few detailed publications on the effect of this process on the composited data that are subsequently taken forward for the estimation process. In this paper, three currently available compositing methods are reviewed and the effects of inappropriate compositing methodologies presented. It is shown through a case study that compositing samples to different lengths leads to changes in the average and variance of the grades in the drillcores in the dataset, which will impact the final estimated value. These differences are exacerbated by breaks or gaps in data where, for a variety of reasons, there has been no data collection or data have been lost. The importance of appropriately treating blank and zero data is also presented. Globally, these differences might be minimal, but locally may be substantial, affecting the efficiency of the estimation and subsequent use of the results in, for example, mine planning and reconciliation. Further detailed investigation of compositing practices is required if the full implications of compositing are to be understood and any induced bias effectively defined.

Jul 10, 2024

INTRODUCTION TO COMPOSITING Individual drill hole samples may vary greatly in size, length, and weight. The sample interval may represent any convenient unit of hole length, and is usually related to the type of drill being used to obtain the sample. Depending upon the type of mineral deposit, it is desirable to group the individual sample values into composite weighted values representative of some particular zone or volume of the ore body. For example, values of several sequential samples of diamond drill core 3 m (10 ft) in length may be grouped together to represent a 12-m (40-ft) sample value over one bench height. On the other hand, several individual sample values taken across the thickness of a stratiform deposit or a vein zone may be weighted together to represent the value of the total thickness at the point of intersection. The choice of composite intervals is usually dictated by the type of mineral deposit and the mining method selected to produce the mineral. The techniques of weighting values from various lengths of samples into a composite value has already been discussed briefly in Chapter 3. Further examples of determining weighted composite values will be given in the following discussion on compositing for various types of mineral deposits. SAMPLE VALUE COMPOSITES AND TYPES OF MINERAL DEPOSITS There are many kinds of mineral deposits, each of which will require special treatment of sample data to obtain the best composite intervals for evaluating the deposit. It cannot always be known before hand what the optimum composite interval will be. Such composite intervals may properly be determined by geologic factors that are often unknown prior [ ]

Jan 1, 1980

Do not write until you have something to say. Think first; then write. In order to be understood, you must know what you wish to say. Clear writing is the consequence of clear thinking. Therefore consider your subject well before you begin to write; ruminate on it; marshal the salient facts in your mind; saturate yourself with the ideas you wish to express and with cognate ideas; then express yourself deliberately. If you are bubbling over with your subject the words will come, but you might as well expect to sail without a breeze as hope to give life to words without the living thought. Here I may advert to the fact that among the uneducated it is a common expectation to acquire the knack of writing without taking the trouble to study the art of literature. I overheard a woman in a suburban train remark to her neighbor: "I'd like to be able to write well without stopping to think about it". She was one of many that would like to do a thing well without the trouble of thinking; but it cannot be done in respect of anything to which thought is essential. The possession of a good voice does not justify a person in expecting to sing successfully to a large audience; before singing in public one has to master the technique of singing; one has to learn first how to breathe properly, how to enunciate, and many other things. The successful singer is an artist, not a megaphone. Most of us would regard a man or a woman without any training in the art of singing as a fool or an impostor if he or she were to give a public concert, yet we do not recognize the equal foolishness and imposture of persons that write books before they have studied the technique of writing. That is why so many books are unreadable, and why many books by clever men are difficult to read. They start to write books before

Jan 1, 1931

By T. A. Rickard

Do not write until you have something to say. Think first; then write. In order to be understood, you must know what you wish to say. Clear writing is the consequence of clear thinking. Therefore consider your subject well before you begin to write; ruminate on it; marshal the salient facts in your mind; saturate yourself with the ideas you wish to express and with cognate ideas; then express yourself deliberately. If you are bubbling over with your subject the words will come, but you might as well expect to sail without a breeze as hope to give life to words without the living thought. Here I may advert to the fact that among the uneducated it is a common expectation to acquire the knack of writing without taking the trouble to study the art of literature. I overheard a woman in a suburban train remark to her neighbor: "I'd like to be able to write well without stopping to think about it". She was one of many that would like to do a thing well without the trouble of thinking; but it cannot be done in respect of anything to which thought is essential. The possession of a good voice does not justify a person in expecting to sing successfully to a large audience; before singing in public one has to master the technique of singing; one has to learn first how to breathe properly, how to enunciate, and many other things. The successful singer is an artist, not a megaphone. Most of us would regard a man or a woman without any training in the art of singing as a fool or an impostor if he or she were to give a public concert, yet we do not recognize the equal foolishness and imposture of persons that write books before they have studied the technique of writing. That is why so many books are unreadable, and why many books by clever men are difficult to read. They start to write books before

Jan 1, 1931

By Ho E

Analyses of several nickel mattes from around the world show a significant variation in their copper content. Typically, matte contains an alloy, heazlewoodite and a copper sulphide phase. The various commercial methods of processing these mattes are reviewed and some of the fundamental factors which determine the choice of leaching system are discussed. Electrochemical studies on pure heazlewoodite and millerite in sulphate and chloride media are compared which show that nickel sulphides react via a series of nickel deficient sulphides and exhibit passivation as nickel is removed. Differences in the electrochemical behaviour of nickel sulphides in chloride media are attributed to greater crystallinity of sulphur and less formation of'NiS2. The electrochemistry of mattes differs because of the presence of alloy and copper. Copper in the matte modifies the potential for alloy dissolution and the rate of anodic dissolution of nickel. At elevated temperatures, Cu(II) in solution exchanges with NiS and completes the leaching of nickel at relatively low potentials without significant oxidation of sulphur to sulphate. It is concluded that there are fundamental advantages to leaching nickel matte in chloride media using Cu(II)/Clz as the oxidant.

Jan 1, 1996