Search Documents

By Ulf G. Gwildis

The Bright water Conveyance System includes 21 km of tunnels mined by two earth pressure balance Tunnel Boring Machines (TBMs) and two slurry TBMs. The probabilistic baseline approach defined in the Geotechnical Baseline Report (GBR) can representatively be verified by use of a comprehensive tracking system to identify face conditions that allows comparison with the baselines. The glacial geology includes a high lateral variation in soil types that, when combined with the pressurized face tunneling methods, creates challenges for documenting face conditions. Baseline tracking using spoil samples and TBM operational parameters provides information to document actual conditions and support resolution of differing site condition claims.

El presente artículo describe la morfología, estratografía y geología de la mina de Cercapuquio. Su geografía consiste en una zona levantada por fenómenos orogenéticos, donde después de un período de glaciación regular y se ha formado en su parte central, la cabecera del río Chacuasmayo ( o Cerca puquio); en la parte oriental, un sistema de valles paralelos entre sí, con lagunas, tributarias del río La Virgen e igualmente, y en la parte occidental, otro sistema parecido de valles paralelos, lagunares, tributarios del río Canipaco.

Aug 1, 1955

Analysis of rock discontinuities, collected using a scanline method, has been undertaken at the Iron Duke open cut mine, on the southern margin of the Middleback Range in the Gawler Craton, South Australia. The iron mineralisation, which is a product of supergene enrichment of carbonate sediments, is located on the W (western) limb of a gently N plunging D2 macrosyncline. Mesofolds plunge shallowly to the NE or steeply to SE, suggesting two shortening events, of which the second produced significant macrofolds. Discontinuities include:faults and shears which display variable orientations, mainly striking WNW dipping steeply N; mesofractures or joints maintaining a well constrained orientation, dipping steeply S, subvertical striking E-W; and bedding surfaces which are folded about a gently N plunging axis. Through this example of the regional control exerted on local discontinuities, it is clear that discontinuities are not randomly distributed as often assumed in purely statistical approaches. Commonly for rocks of any age there is a distinct discontinuity pattern, reflecting the geological deformation history. If the controls exerted on local rock discontinuities can be determined and assigned a number related to their significance, the way forward is available to develop a site specifc knowledge base that can make realistic predictions for any position in a given rock mass. Such a procedure would involve assessment of the regional geology, linked to scanned discontinuities either via manual or automatic means. Recent advances in automatic scanning rock faces (eg by the I-SiTE Laser Radar) to determine discontinuities distributions, enable the rapid calculation of rock characteristics. This is a significant advance in rock engineering, providing a method of safe and quick collection of data. However it creates problems in the presence of an increase in the geotechnical data available, which should be assessed in the context of the regional geology. Although techniques are underway to analyse post-blast discontinuities, the next signifant potential advance in this area could be the integration of a knowledge based system to assess discontinuities ahead of mining, incorporating regional assessment and human intuition.

Jan 1, 2000

The area between Merrygoen and Digilah is located on a structural high that separates the Sydney Basin from the Great Artesian Basin, and hence the stratigraphic succession of younger rocks overlying the basement is relatively thin. The stratigraphy is briefly described and it is shown that fluvial sedimentation prevailed from Upper Permian through to Middle Jurassic times. Flint clays occur in the Permian, Triassic and Jurassic but only those in the Jurassic appear to have commercial value at present. The chemical, mineralogical, and physical properties of the flint clays are discussed.

Jan 1, 1973

By Juan Oswaldo Alfaro, Angel C. Nuñez, Hildebrando A. Cóndor

Se ha desarrollado un software para facilitar la evaluación del proceso molienda-clasificación en plantas concentradoras. Se ha modelado en UML-Lenguaje Unificado de Modelado; los datos e información se almacenó en SQL Server; se programó en Java (Programación Orientada a Objetos). Investigación Aplicada y Cuantitativa obteniendo como resultados un Software para Circuito de Molienda-Clasificación (Directa e Integral).

Sep 1, 2017

By A. Ebrahimabadi

Roadheaders are very versatile excavation machines used in tunnelling, mine development, and mine production for soft to medium strength rock formations. Performance prediction is an important factor for successful roadheader application and generally deals with machine selection, production rate and bit consumption. Among many different parameters, brittleness is also one of the material properties related to breakage characteristics and can be used as a cuttability parameter from a mechanical excavation point of view. The main objective of the research study is to contribute the brittleness of rock excavated to construct a new empirical equation for predicting the performance of roadheaders in different material and operational conditions. In this regard, a new performance prediction model for medium duty roadheaders based on a brittleness index (BI) is presented. In this study, rock mass brittleness index (RMBI) is defined in order to investigate the influence of BI on roadheader performance. RMBI is an index which can be used to relate the intact and rock mass characteristics to machine performance. Results demonstrated that RMBI is highly correlated to instantaneous cutting rate (ICR) (R²=0.94). Moreover, through the further analysis and normalization, the pick consumption index (PCI) was introduced as a parameter having a good relation with pick or bit consumption rates (PCR) (R²=0.79). Finally, the new predictive models for ICR and PCR showed very good correlations with the actual measured values. Keywords Performance prediction, roadheader, brittleness index, mechanical excavation.

Jan 1, 2011

This paper presents a study about reopening of a quarry near to the geothermal region of Kntahya, Turkey. The production method was gallery blasting which resulted in very high ground vibrations. Therefore the quarry had been closed down by the local authorities about 12 years ago due to possible damages to the geothermal resources. In order to reopen the quarry, reserve estimation and production planning studies needs to be carried out as well as applying environmentally sensitive production method. The result of reserve estimation studies showed approximately 12.5 Mt reserve in the area. The market studies indicated that annual production of 600 000 tonnes could be sold. These results justify to reopen the quarry. In order to overcome environmental problems, bench blasting production method instead of gallery blasting has been planned. This method enables to design a drilling blasting pattern that will almost result in no ground vibrations.

Dec 6, 2010

Eco-Efficient Gravity Separation Solutions in India Sustainable development and social responsibility issues are a principal aspect of mineral processing operations around the world. With the need for more environmentally effective technologies, some gravity separation systems have provided eco-efficient mineral processing solutions in places where it is not otherwise viable because of lack of fresh water or for other environmental reasons. Advanced spiral separation technologies developed in Australia offer a cost effective and environmentally viable way to process minerals. In particular, we review recent case studies of spiral plants commissioned in India where environmentally sustainable solutions to design problems included the use of spirals operated with sea water and the use of high capacity (HC) spirals to provide low consumption of energy and materials and a reduced plant footprint. This paper evaluates the performance of various spiral plants in India and how critical environmental issues which affect the overall viability of wet concentrating processes where resolved.

Sep 13, 2010

By W. G. Pariseau

Equivalent elastic properties of discontinuously jointed rock masses are computed using a non-representative volume element(NRVE) approach within a three dimensional finite element program. Joint persistence, defined as the percentage of a joint plane that is actually occupied by joint material, is used in the NRVE computations as a step towards greater realism in stability analysis of mine openings. Persistence p is also the probability that a segment of a joint plane is occupied by joint material. Computations reveal a threshold phenomenon in jointed rock mass moduli similar to that observed in percolation theory. A rapid decrease in moduli occurs above a critical value pc(about 0.6). A detailed analysis of the well-known solution for stress about a circular opening in isotropic, elastic ground illustrates the effects of joint set orientation, spacing and persistence. Although stable “on average”, joint segment failures reveal a threat to stability and point towards rational design of reinforcement or support of discontinuously jointed rock masses.

Jan 1, 2003

By D FitzGerald, S Jakica, R Paterson, J Silic

A new 2.5D airborne electromagnetic (AEM) algorithm has been developed by Intrepid Geophysics and Jovan Silic & Associates. The advantage of 2.5D (2D geology, 3D source) AEM inversion in 3D geological mapping applications and identification of conductive drilling targets, compared to the more commonly used conductivity-depth imaging (CDI) transforms or 1D inversions, are demonstrated using examples from banded iron formations (BIFs) and other geological settings. We show emerging AEM systems are capable of providing estimates of economic rock unit thicknesses, dips and fault definition at an accuracy that mitigates the need for pattern drilling.The 2.5D inversion application used in this work and described in Silic et al (2015) is a substantially changed version of ArjunAir (Wilson, Raiche and Sugeng, 2006), a product of CSIRO/AMIRA project P223F. The changes include a new forward model algorithm and a new inversion solver. The application enables the accurate simulation of 3D source excitation for full domain models inclusive of topography, non-conforming boundaries and very high resistivity contrasts. Solution is accurate for a geoelectrical cross-section, which is relatively constant along a strike length that exceeds the AEM system footprint.The major innovation includes a new inversion solver with adaptive regularisation, which allows the incorporation of a misfit to the reference model and the model smoothness function.Memory usage has been dramatically reduced and is estimated prior to execution. For speed the software has been parallelised using Intel message passing interface (MPI) and can be used on standard computing hardware or computing clusters. Data from survey lines with lengths exceeding 100 km can be inverted on high end laptop computers.We allow flexibility in the selection of components and in the estimation of noise.AEM inversion examples are shown for surveys from BIFs, base metals (volcanogenic massive sulfides) and geological mapping projects and the results are compared with known geology and drilling. We demonstrate the much improved mapping and target definition delivered by this inversion method when compared with the other more common transforms or inversion methods used on these projects.CITATION:Paterson, R, Silic, J, FitzGerald, D and Jakica, S, 2017. High accuracy .D airborne electromagnetic inversion method for banded iron formation and other geological settings, in Proceedings Iron Ore 2017, pp 319–330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By W. A. Wood, H. M. Bendler

Cylindrical fatigue specimens of OFHC* copper were subjected to alternating torsion while under axial tension. The superimposed tension strongly influenced the fatigue life of the specimens as well as causing characteristic changes in the structure of the fissures that form and develop throughout the life of the specimen. A further effect of the superimposed tension is a continuous extension of the specimen throughout its life in a manner formally similar to creep at elevated temperatures. RECENTLY, studies of the structural changes leading to fracture of metals by fatigue have been made by a technique which reveals, in section, the lattice distortion arising from slip movements inside the metal and the disturbances built up by these slip movements at the metal surface.1'2 According to this approach, fatigue develops as follows: a) fine slip movements concentrate in bands, producing little strain-hardening and thus permitting abnormal totals of plastic strain before fracture and, therefore, abnormal amounts of lattice distortion along each slip band; b) both forward and backward slip movements occur in each band which, according to their distribution across the band, may build up surface disturbances that include sharp notches; c) these notches early in the life of a specimen penetrate the distorted slip zones and transform them into deep, fine fissures; d) the fissures on continued cycling locally saturate the metal and cause local collapse in the form of a microcrack. Thus, the significant consequence of fatigue or cyclic

Jan 1, 1962

Mr. Murray said: Having recently returned from a visit to America, it may be of interest to members to hear something from me of the mining fields and metallurgical works which I had the opportunity of seeing, and the impressions which I formed concerning general practice and conditions there, as compared with our Australian standards in the mining industry, and in matters generally.The most striking feature of the North American continent is thehuge plan upon which Nature has built, the multiplicity of immense mountains, rivers, and lakes, the snow-covered tops of the former forming reservoirs for the latter during the summer months, being most impressive to the Australian visitor. Starting from Vancouver I travelled east for over 500 miles through the wonderful Canadian...

Jan 1, 1927

By Edgar Roque, Edwin Cereceda

El método de explotación por Bench and Fill tiene importantes ventajas como menores costos y mejores rentabilidades. Asimismo, entre los factores que caracterizan a este método son la dilución y la fragmentación con respecto a otros métodos convencionales como corte y relleno, shrinkage, cámaras y pilares, etc. Es por ello, que se le debe dar una importancia especial al control de la dilución y fragmentación, tomando en consideración variables generadas en la voladura. Normalmente estos controles se efectúan durante la voladura en Bench and Fill, generalizando los resultados para un nivel completo los cuales están sujetos a prueba y error, sin considerar ciertas características del macizo en diferentes zonas de ese nivel.

Sep 1, 2017

By N Weerasekara, M Powell, P Toor

The effect of liner wear on SAG mill performance has gained much attention in recent years. It is commonly observed that the three key performance criteria of SAG milling; throughput, power and product size all improve as the liner wears.The increase in throughput is generally ascribed to the increase in the grate apertures and the increase in mill volume due to the wear of these components. Whilst the decrease in product size is attributed to the reduction in lifter height and angle, resulting in more breakage by means of attrition and abrasion.Though it is widely acknowledged that the wearing of liner components such as Lifters, Plates and Grates have a significant impact on mill performance, their individual contribution to changes in mill performance has been unclear, and resultantly lead to questions like; what percentage of the throughput increase can be attributed to the increase in mill volume (plate wear)? and how much can be attributed to the increase in grate aperture (grate wear)?It has been found that through the use of grinding surveys, analysis of production data and JKSimMet it was possible to separate the effects of changing liner profile, increasing mill diameter and increasing grate aperture on the mill performance allowing for the quantification of each.The outlined methodology allows for both troubleshooting of problem liner components which reduce milling efficiency in their wear life as well as providing a basis for a more quantitative approach to liner design and reline scheduling.CITATION:Toor, P, Powell, M, Hilden, M and Weerasekara, N, 2015. Understanding the effects of liner wear on semi-autogenous grinding mill performance, in Proceedings MetPlant 2015, pp 150–161 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

A substantial proportion of current and historic West Coast gold production comes from deposits situated around the margins of æice ageÆ glaciers. Gold has been eroded and transported by glacial ice then deposited in till and outwash gravel. The interplay between fluvial and glacial processes, climate, basement geology, tectonic uplift, sediment supply and sea level dictates many aspects of the development of the West Coast landscape. The way in which the external forcing factors interact is crucial in determining the gold content of placer deposits in this region. The following is an outline of some of the factors that influence the gold distribution in vicinity of glacial margins.

Jan 1, 2000

The published liquidus data on the Pb-PbS system have been correlated on the basis of one-coefficient Margules equations. Thermodynamic properties of the components of this system have been obtained, and it has also been found that the calculated miscibility gap of this system exists over a very narrow range of temperature (1041 to 1058°C).

Jan 1, 1972

By Gabriel S. Esterhuizen, Jarek Jakubec

In 2000, Laubscher’s Mining Rock Mass Rating (MRMR) classification system was updated and published. The new system brought a few fundamental changes that were in direct response to the challenges and problems encountered when applying the classification system in the mining environment, specifically caving operations. The fundamental changes introduced into the MRMR system in 2000 were the abandonment of the Rock Quality Designation (RQD) as an input parameter, accounting for healed and cemented joints, and the concept of rock block strength. The objective of this paper is not to discuss the role and usefulness of classification systems; the fact that classification systems are widely used in every stage of mining projects speaks for itself. This paper discusses some of the experiences gained with the MRMR 2000 system in various mining projects and shows how the changes to the system have resulted in improved assessment of rock mass conditions. Issues related to core logging for rock mass assessment are also presented.

Jan 5, 2007

By R. Weideman, M. Le Roux, F. B. Waanders, Q. P. Campbell, E. Fosso-Kankeu, D. Moyakhe

"*Paper written on project work carried out in partial fulfilment of B.Eng (Chemical Engineering) degreeSynopsisSpent coffee grounds were transformed into biochar using a hydrothermal method. Some of the biochar product was pre-treated through surfactant impregnation with sodium dodecyl sulphate (SDS) to enhance its adsorption capacity. The non-treated(NT) and pre-treated(PT) biochars were characterized using FTIR spectroscopy and SEM-EDS analyses, which revealed that the products had the potential for adsorption of heavy metals from solution and confirmed the successful impregnation of biochar with SDS surfactant. The two adsorbents were then used for the removal of cadmium from solution and the adsorption behavior and capacity determined through adsorption isotherm, kinetic, and thermodynamic studies. It was found that the cadmium was adsorbed in several concentric layers on the surface of the adsorbents through a chemisorption mechanism. The PT biochar was identified as a superior adsorbent, with a capacity of qe = 10.67 mg/g compared to the NT biochar with qe = 4.82 mg/g. The adsorption of cadmium onto the PT biochar was further determined to be spontaneous and endothermic. It was therefore concluded that the PT biochar shows potential as an adsorbent and could be considered for implementation in the treatment of metal-polluted effluents. IntroductionCoal mining operations are notorious for producing large amounts of waste tailings, which are disposed of in the form of a slurry on tailings dams. This inadvertently contributes towards environmental problems (Jin, Mansour, and Thomas, 2017). Heavy metals are one of the most common pollutants that originate from solid mine waste disposal facilities, and these can leach into groundwater supplies, contaminating them and rendering the water unsuited for human consumption (Salomons, 1995). Cadmium occurs in conjunction with metalliferous ores and can cause severe damage to agricultural soils and drinking water supplies in the vicinity of mining sites (Dudka et al., 1995). It has a tendency to migrate into the surrounding vegetation, which in turn can cause harm to humans and animals when consumed (Marquez et al., 2018)."

Jul 1, 2019

Whilst much has been written in past years by geologists, scientists, mining engineers, etc., regarding the well·known and justly notorious anticlinal, or, as they are more commonly known, " saddle" reefs of Bendigo, comparatively little noticehas been given to the synclinal or "inverted saddle "reefs and their relationship with each other. In taking up the question of the synclinal folds, I recognise that it is a large undertaking to confine within the limits of a short paper, and at the same time convey a comprehensive idea of their characteristics, and the importance of their relationship with the anticlinal folds, in the general question of practical mining. However, from a practical point of view I consider the question of great importance, and if an interest in it can be awakened, more particularly among practical men, the object of this paper will be achieved.Before entering into the subject I must briefly state some facts, and perhaps some theories, in respect to the deposition of the Lower Silurian rocks, and their subsequent buckling up, as now seen on the Bendigo gold-field. At the same time, I do not intend to go very closely into the geological aspect of the question, as I wish the paper to be considered as a practical one.

Jan 1, 1902

By Jamie Bonner, Ray Hutton, Taro Nonaka

The Nancy Creek Tunnel is a deep tunnel, designed to store and convey wastewater by diverting flows from trunk sewers currently at or near capacity in the northwest of the City of Atlanta. The tunnel, constructed in hard rock, has an overall length of 13,300 m (43,700 ft), and a finished diameter of 4.9 m (16 ft). The project is currently under construction by a joint venture of Obayashi/CJB for the City’s Department of Watershed Management. This paper describes the contractor’s techniques and equipment, as well as discussing challenges which were overcome. The project is scheduled to be complete in October 2005.

Jan 1, 2005