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The minerals industry contributes to the economic growth, prosperity and quality of life of nations, particularly in areas where there might be limited opportunities for employment in other sectors. However, notwithstanding their economic importance, the minerals extraction and processing industries are considered to have significant impacts on the surrounding environment. In recent years many mines have implemented modern monitoring technology and modelling of the monitored environmental parameters to provide scientifically proven indicators about the state of the environment. The flexibility required by the minerals industry to respond dynamically to a changing natural, social and economic environment has become a major consideration. Whilst the notion of continuous improvement is embodied within most environmental management systems, what is now required is a structured audit trail which tracks the flow of resources through the production process to the ultimate environmental impact associated with their consumption, transformation and disposal. Imperial College is coordinating an EC funded project, which is developing a methodology to minimise the ?full life-cycle? impact of metalliferous mining projects, adopting an integrated approach to production and process design, and the costs involved. In order to develop a life cycle assessment (LCA) system that will incorporate different types of data related to the minerals extraction operations, a data inventory was designed and coded in an object-relational database model. The calculation procedures accounting for the input/output balance of the alternative scenarios for mining production, processing, waste disposal, monitoring, and their financial implications are being programmed into a software system. This paper presents the rational and innovative aspects of this work. The methodology developed for the life cycle database is illustrated for the mining production and gaseous emissions components of the system.

Jan 1, 2003

Marble has been recognized as a valuable natural resource ever since ancient times. Due to its peculiar aesthetic and technical characteristics as well as the lithotype uniqueness, it has widely been appreciated over the past centuries. In present times its production and demand are enjoying an increasing trend, with comparatively high market prices. All this considered, marble can be included among these natural resources whose exploitation provided, and still provides, an important contribution to the growth of the economic system. Nevertheless, there is at least one more important reason that makes marble a valued resource. For ages, marble represented one of the most important raw materials for sculpture sand architectural masterpieces, which constitute part of the cultural heritage of mankind. With this in mind, the value of marble is strictly related to its extraordinary capability to preserve cultural heritage and therefore to convey civilization from past to future generations. In other words, the role of marble should be recognized as being of the utmost importance in order to attain an overall objective of ?cultural sustainability?, that is, the assurance of the inter-generational flow of the cultural heritage capital. To achieve this sustainability goal, the priorities should be to protect and preserve the world?s artistic and architectural historical heritage, which require restoration works. In this field, a very il task is entrusted to the extractive industry: this industry, in cooperation with historians, art experts and public authorities, is in charge of detecting and supplying historical stones for restoration purposes, taking into consideration that, in order to restore a monument in a correct way, the same lithotypes the monument was made from are needed. These marbles are often no longer in production, so that it becomes necessary to find the location of the original quarries, as only there is it possible to extract even the small quantities of stones that are needed. In this case, the stone, located in its geological context, could have such valued characteristics as to be considered an important public asset and consequently a resource to be preserved and protected even beyond the market conditions. This important task should be carried out by the public administration through a targeted intervention of territorial planning and monitoring, which could include the support for the specific extractive activity.

Jan 1, 2003

By K. Tempel

In December of 1999, Newmont Mining Corporation’s Eastern Nevada Operations commissioned its commercial biooxidation facility. The commercial biooxidation facility is a refractory gold whole ore heap process that uses bacteria to assist with the oxidation of sulfide minerals thus liberating occluded gold for further processing by cyanide for gold extraction. Before the commercial biooxidation facility was started, a decade of research went in to developing this state-of-the-art process. During final design and construction of the commercial facility a decline in gold price necessitated cost saving and project scope changes. As a result, the biooxidation process experienced many challenges. Some of the more significant challenges include poor heap permeability due to haul truck stacking, unhealthy bacteria population due to a lack of solution aeration, and insufficient biooxidation time because of limited pad space and high carbonate content in the ore. This paper discusses the many challenges encountered and addressed during the first 2-3 years of commercial biooxidation operation.

Jan 1, 2003

By V. N. Kazakidis

With increased levels of automation, capitalization, and empowerment of citizens, the traditional axis of labour versus capital or national government versus capital, upon which the allocation of benefits from a mining project was traditionally based, has shifted primarily to a capital versus community axis. In light of this paradigm shift, it is critical for the sustainability of mining that economic indicators be considered at the pre-feasibility, feasibility, and permitting stages of a project. Such indicators should emphasize the ?ripple effect? of the economic impact of a capital-intensive mining investment on a region due to outsourcing, as well as the diversified spin-off opportunities and the technological advances that can be exploited by local communities.

Jan 1, 2003

By L. H. Michaud

"Albian Sands Energy (ASE), an oil sands surface mining and extraction operation, is currently undergoing start-up and is scheduled to ramp-up to full production by mid-2003. Startup includes the selection and implementation of over 75 IT systems or computer applications which include: engineering applications; systems required to control mining activities, maintenance, the processing plant and utilities; and also systems required to run the company, such as human resources, finances and inventory/ warehousing.This paper outlines the processes used for the selection, implementation and integration of these systems in order to optimize the use of information and to meet the technical, business and IT requirements of the company. The first step in ASE’s approach to identifying system requirements is the development of a business activity model, outlining all tasks involved in running the operations. The computer applications required to accomplish each task are then identified by having the IT team work closely with each technical and business unit. Historically, at some companies, the selection of systems has been led by the IT team or by consultants, with little input from the technical or business units. Typically, this results in products that do not meet the company’s expectations. To ensure a more positive outcome, ASE believes that it is imperative that the company’s technical and business people be closely involved in the selection process.Integration of the IT systems is also key, including linking all applications through a data warehouse and EDMS. Over 120 required integrations have been identified. This ensures the storage of all data in only one location, data security, and easy data and document retrieval for all requirements throughout the company"

Jan 1, 2003

By Ramon V. V de Araújo, Roberto B. E Trindade, Pablo R. Fica-Piras

"Lead has been reported to affect blood vessels and kidneys. It also produces adverse effects in the mental and physical development of children and nervous system of adults. It is also considered as a possible cause of cancer. Because of all these threats to the human life, the reduction of its environmental occurrence, by means of recycling, is an important additional advantage to the usual ones derived of the procedures of the secondary metallurgy: lead can be recycled several times maintaining its characteristics equivalent to the primary one.Furthermore, this way of producing the metal avoids the environmental impacts of primary lead melting. Also, as an additional advantage, it triggers the metallurgical process with a raw material in what we observe higher lead content than in the natural ores. Some of the potential sources for these purposes are: ashes, slags, electrode residues, anodic muds, spent electrolytes, solid and liquid wastes, industrial or automotive catalysts, worn-out or obsolete equipment components and/or final consumption products.About 40% of world’s lead production comes from automotive batteries, mainly composed of four parts: plastic box, electrolyte (diluted sulphuric acid), contacts and connectors of Pd-Sb and plates (PbSO4, PbO2 and PbO). The plates represent 75% of the total mass. Metallic parts can be melted at moderate temperatures and then refined. The remaining fraction, constituted by the non-metallic portions, can be recovered by hydro and electro-metallurgical routes. These routes are preferred instead of pyrometallurgical ones due to the ultimate emissions of lead particulates and sulphur dioxide.The principal constituent of the residual paste of batteries is the lead sulphate. In this process, the paste is treated in two stages: in the first, lixiviating with Na2CO3 (desulphurization of the paste), obtaining PbCO3 and Na2SO4; in the second, the lead carbonate is lixiviated with HNO3, producing Pb(NO3)2, soluble, that can be converted to metallic lead by electrolysis. The reaction of PbSO4 with Na2CO3 in aqueous solutions is fast: the global rate is limited by the diffusion of the carbonate ions inside the reaction medium."

Jan 1, 2003

By R. Poisel, C. Scavia, Preh A., W. Roth, M. Pirulli

ABSTRACT: Two methodologies for the three-dimensional simulation of the run out of rock avalanches are presented: one based on a granular approach and the other based on a continuum equivalent approach. An evaluation of the possible run out area of the Oselitzenbach landslide (Carnic Alps, Austria) has been carried out applying the two methodologies. The combined use of these two approaches makes it possible a comprehensive assessment of the run out area. RESUME: Deux méthodologies pour la simulation tridimensionnelle de la propagation des avalanches rocheuses sont présentées: la première est basée sur un modèle de type granulaire et la deuxième sur un modèle du continu équivalent. Une évaluation de la propagation éventuelle de l’avalanche de Oselitzenbach (Alpes Carniche, Autriche) a été réalisée en utilisant les deux méthodologies. Les résultats obtenus montrent que la combinaison des deux approches rend possible une analyse plus complète de la phase de propagation. KURZFASSUNG: Für die dreidimensionale Modellierung eines Felsmassensturzes (sturzstrom) werden zwei Methoden, eine granulare und eine kontinuumsmechanische Methode, vorgestellt. Beide Methoden wurden zur Abschätzung der Ausbreitung (runout) der Massenbewegung Oselitzenbach (Karnische Alpen, Österreich) herangezogen. Die kombinierte Anwendung beider Methoden ermöglichte eine umfassende Beurteilung des möglichen Ausbreitungsbereichs.

Jan 1, 2003

By Henry Hu

In high pressure die casting processes, proper control of temperature die yields a high casting production rate and superior quality components, Die temperature is usually influenced by various die design and process parameters such as size and location of intemal water cooling lines, flow rates of cooling lines, and pouring temperature of molten metal. Among them, the cooling water flow rate plays a major role in controlling thermal pattern of the die_ In order to develop an effective control strategy, data of local die temperature must be collected and analyzed, In this study, a PC-based data acquisition and control system (DACS) for die temperature control has been designed, and established, The developed DACS has three input channels for temperature signals and one input channel for water flow rate signals, as well as one output channel for a water pump, and is capable of displaying data in both curve format and value format. Implementation of the DACS in a laboratory setup has also been attempted, It should be pointed out that more advanced control mechanisms can be potentially integrated into this system in future,

Jan 1, 2003

By H. L. Ehrlich

Modes of microbial attack of metal carbonates, metal silicates, metal oxides and metal sulfides are summarized. The current status of microbial redox mechanisms, whereby metals in metal oxides and sulfides are mobilized, is discussed. Opposing theories of a single mode of attack involving interaction with a microbially produced reductant or oxidant in the bulk phase and of dual modes of attack involving a reaction requiring physical contact between microbe and mineral surface on the one hand and microbial production of a reductant or oxidant in the bulk phase that reacts with the mineral on the other hand are considered. No one mode when finally completely unraveled should be expected to fit all cases. Some biochemical, electronmicroscopic and spectrophotometric approaches for elucidation of missing details of different modes are suggested. Key words: Bioleaching, Biobeneficiation, Metal mobilization

Jan 1, 2003

By J. L. van Niekerk, J. Gunaselvam

This study investigates the use of appropriate seating systems for the control of whole-body vibration exposure in vehicles used in the SA mining industry. Six suspension seats were tested with six test subjects to determine the most suitable seat for an articulated dump truck based on the EM1 requirement in ISO 7096 (2000) standards. Transmissibility functions were measured in the laboratory using the newly commissioned Dynamic Seat Testing Facility with two excitation levels of 1m/s2 and 2 m/s2 r.m.s. in the 0.5 - 30 Hz frequency range. SEAT values were calculated for two input spectrums, the EM1 input spectrum specified as in ISO 7096:2000 and measured road vibration data measured on a typical articulated dump truck. The averaged SEAT value calculations indicated that not one of the seats will qualify as an ISO 7096 (2000) suspension seat but that it is possible to select a seat that will significantly reduce the vibration the driver will be exposed to.

Jan 1, 2003

By John Ralston, Jona Addai-Mensah, Patience Mpofu

The flocculation and dewatering behaviour of kaolinite (non swelling) and smectite (swelling) clay dispersions has been investigated using hydrolysable metal ions Mn(II) and Ca(II) and anionic polyacrylamide-acrylate copolymer (PAM) at pH 7.5 and 10.5. A pH-dependent, specific metal ion adsorption behaviour, accompanied by a marked reduction in particle zeta potential and slurry shear yield stress, was observed to have a profound influence on the colloid stability of both types of clays. Due to the differences in the cation exchange capacity, the smectite clay dispersion required a higher amount of metal ions than kaolinite dispersion to produce similar effects. The adsorption density of the anionic PAM at the negatively charged clay particle surfaces correlated well with metal ion hydrolysis and adsorption behaviour, all of which had a strong effect on slurry settling rate and extent of consolidation. At pH 7.5 where Mn(II) ions hydrolyse, metal ion and flocculant adsorption densities were both greater in the presence of Mn(II) than Ca(II) ions. At pH 10.5, however, where Ca(II) ions begins to hydrolyse, higher adsorption densities were observed for Ca(II) ions in comparison with Mn(II) ions, as the latter hydrolysed completely and precipitated. The metal ion mediated flocculant adsorption led to improved hydrogen bond driven particle bridging and facilitated charge neutralisation flocculation mechanisms which significantly enhanced the dewaterability of both clay dispersions.

Jan 1, 2003

By Carin Laubscher, Francis W. Petersen, Jaap P. Smit

Waste streams, such as acid mine drainage, are often characterised by low pH values and high concentrations of heavy metals, dissolved solids, calcium and sulphates. Although lime remediation effectively removes most of the heavy metals as hydroxides, it is less effective at lowering levels of sulphates. Various methods of removing sulphates from effluents exist, such as precipitation with lime, precipitation with barium salts, co-precipitation with calcium carbonate, reverse osmosis, and ion exchange. Mintek developed a chemical precipitation (SAVMIN) process to treat acid mine drainage, which entails the addition of lime to precipitate the metal hydroxides, and the subsequent formation (precipitation) of calcium sulphoaluminate or ettringite. The key to the viability of the new technology lies in the correct use, regeneration and recycling of Al(OH)3 used to precipitate the ettringite. The water produced by this process is suitable for disposal to watercourses or for agricultural, domestic or industrial consumption. No brines are produced as the salts are converted to solid hydroxides, gypsum and calcium carbonate. The technology has been tested on several different waters in pilot plant campaigns. Results obtained indicate that potable water can be produced (containing less than 200 mg/L sulphate and no heavy metals) as long as the monavalent ions (Na+, Cl-, etc.) are within limits.

Jan 1, 2003

By D. P. Harding

Quick, inexpensive and accurate mineral-phase identification is of utmost importance to applied mineralogists. The precise relationship between the intensity of measured backscattered electrons in a scanning electron microscope and the average atomic number of the specimen is still argued. Nevertheless, much can be gained by using backscattered electron images to identify mineral phases in a specimen. An application was developed to facilitate this method and makes it a practical, inexpensive and valuable option in many mineralogical investigations. Keywords: Mineral identification, Scanning electron microscope, Backscattered electron detectors

Jan 1, 2003

By D Craw

At Reefton, mesothermal gold deposits occur in the Ordovician Greenland Group basement and bituminous coal deposits occur in overlying Eocene Brunner Coal Measures. These different resource types occur in close proximity to one another in the same topography, vegetation and climate. Both types of resources have been mined for many years and as a result historic mining areas discharge water with chemistry reflecting the mineralogy of the deposits. Coal measures release natural acid rock drainage throughout the region due to oxidation of pyrite in coal and associated sediments. Levels of acidity are increased in mining areas, and pH near three is common. Gold mines contain pyrite, arsenopyrite and stibnite. Discharge waters from these sites have pH near seven because of the high acid neutralising capacity of the basement rocks. Both coal and gold mining sites have iron oxyhydroxide precipitates in drainage waters. These precipitates are more abundant at gold mining sites, and one deposit is up to 5 m thick. Iron oxyhydroxide at coal mine sites contain Zn (up to 89 ppm), Ni (up to 10 ppm), As (up to 163 ppm), Cr (up to 23 ppm), Pb (up to 16), and Cu (up to 11 ppm). Jarosite group minerals have been identified in the coalmine iron oxyhydroxide, although most of the material is amorphous. Gold mine iron oxyhydroxide contains Zn (up to 353 ppm), Ni (up to 592 ppm), Cr (up to 17 ppm), Cu (up to 72 ppm), Pb (up to 29 ppm), Sb (up to 230 ppm), and this material is particularly high in As (up to 20 wt per cent). Most of the material is amorphous but distinctive zones (mm scale) are As rich (up to 30 wt per cent As oxide). Pharmacosiderite, K2Fe4(As04)3 (OH)5.6.3H20, is a secondary mineral in one deposit. These iron oxyhydroxide deposits are useful indicators for the metals mobilised into the environment by oxidation in the historic workings.

Jan 1, 2003

By A. Kazemi, M. A. Ahmadi

Pressure tunnels are constructed nurously in related with powerhouse. In some cases, according to high internal water pressure, rock mass around tunnel can seldom suffer this pressure. So installation of concrete lining which interacts with rock mass and suffers parts of this pressure and transfers the rest of the pressure to the rock. In this paper hydromechanical interaction between rock and lining is investigated. With using empirical and numerical methods concrete lining for Symareh waterway is designed. Initial support of 10 cm reinforced shotcret with wire mesh and rock bolts pattern of 2.5*2.5 m with length of 4 m is suggested. By using FLAC package final lining with paying attention to axial force and momentum in reinforced concrete was designed. Reinforced concrete with 60 cm thickness and two rows of bars, 18 mm diameter and 20 cm spacing are designed. Also for preventing cracks in concrete which caused by the change of temperature and shrinkage, bars with 10 mm diameter and 25 cm spacing, and also bars with 8 mm diameter and 10 cm as minimum shear bars are suggested. Plusieurs galeries en pression se construisent en liaison avec les centrales électriques. Dans certaines galeries, suite à une haute pression interne de l'eau, le massif rocheux autour de la galerie ne peut pas supporter cette pression. L'installation d'une couche de béton a l'intérieur de la galerie donc réagit avec les roches et support d'une partie de cette pression et transfère le reste de la pression aux roches. Dans ce papier, l'interaction hydromécanique entre la roche et la couche en béton a été étudiée. En se basant sur les méthodes empiriques et numériques le système de support de galerie de passage d'eau de Saymareh a été conçu. Un soutènement initial d'une épaisseur de 10 cm de béton étant renforcé par un grill métallique et une maille de boulon (2.5 * 2.5 m) d'une longueur de 4 m a été proposé. En utilisant le logiciel de FlAC, la couche finale en béton selon les forces dans le béton a été conçue. Le béton renforcé d'une épaisseur de 60 cm et deux ranges d'armateurs (18 mm de diamètre) avec un intervalle de 20 cm a été conçu. De plus; pour éviter des fissures dans le béton suite au changement de la température et de l'extraction, des armateurs de 10 mm de diamètre et de 25 cm d'intervalle pour augmenter la résistance au sciesiement du béton ont été proposes Unter Druck stehende Tunnels werden hauptsaechlich im Zusammenhang mit Kraftwerken gebaut. In einigen Faellen, wo der Wasserdruck zu hoch ist, Kann selten die Felsenmasse diesen hoehen Druck allein aufnehwen. Deshalb werden sie mit Betonauskleidung versehen, die wegen guter Wechelwirkung mit der Felsenmasse einen Hauptanteil des Druckes aufnehmen Kann, wobei der Rest an die Felsenmesse weitergeleitet wird. In dieser Arbeit wird die hydromechanische Wechelwirkung zwischen der Gesteinmasse und der Auskleidung untersucht. Mit Hilfe empirischen und numerischen Verfahren sowie Kombination der beiden wurde eine Betonauskleidung fuer die Symareh Wasser Kannal koustruiert. Als erstes wurde ein 10Cm dicker armierter Beton mit einem Mashengitter von 2.5*2.5 sowie den gleichen Felsbolzenabstaenden und einer Laenge von 4 m vorgeschlagen. Mit Hilfe des FLAC Programms wurde die Hauptauskleidung unter Beruecksichtigung von Axialkraeften und Momenten im Stahlbeton koustruiert. Der 60 Cm dicke Stahlbeton wurde mit zwei Reihen von Stangen, 8 mm im Durchmesser und in Abstaenden von 20 Cm koustruiert. Ferner im Sinne der Vorbeugung gegen Rissen im Beton, die durch Temperatur aendeungen und Schrumpfungen bedingt sind, wurden Stangen mit 10 mm Durchmesser und 2.5 Cm Abstaenden zur Erhoehung vor Scherfestigkeit des Betons vorgeschlagen.

Jan 1, 2003

By M D. Melville, B C. T Macdonald, T D. W

The surface waters in regions with acid sulfate soils (ASS) can contain high concentrations of acidity and dissolved metals. These soils cause problems for agriculture, construction and development. The water can be neutralised through many techniques, however a technique that is low in maintenance and low in cost is most desirable. Due to the vast spread of ASS along AustraliaÆs coastline an expensive and high maintenance solution would not be cost-effective. In this study, a passive treatment system that has been used to neutralise acid rock drainage has been applied to treat ASS water. This system is commonly referred to as an oxic limestone drain (OLD) or an anoxic limestone drain (ALD) depending on the waters dissolved oxygen concentration. The system that has been developed for ASS has a similar closed system to the OLD or ALD, that traps the carbon dioxide which forms when limestone reacts with acidic water. It has been called a closed tank reactor (CTR) and is constructed by placing limestone into an airtight tank. A common problem that will occur when acidic water with a high concentration of dissolved metals reacts with limestone is the formation of metal oxy-hydroxide precipitates. These precipitates can coat or armour the limestone and reduce its reactivity. To minimise the accumulation of precipitates in the CTR, perforated subdrains have been installed. It is anticipated that high water pressure and flow through the subdrains will remove some precipitates. A sump has also been installed at the base of the tank to collect precipitates that settle under gravity. The CTR has been tested for 70 days at a sugar cane farm located at McLeods Creek, NSW. Within this time the sump and subdrains have been used to flush the system. An orange solution was produced during flushing and it is believed to contain iron and aluminium precipitates. The initial performance of the CTR raised pH by at least one unit. Almost all dissolved aluminium was removed and more than half the dissolved iron. The total titratable acidity ranged from 17 - 92 mg/L CaCO3 in the initial month of monitoring. After passing through the CTR the acidity was reduced to zero. The performance of the CTR during the last few days of monitoring decreased. This is believed to be due to a pulse of water with higher acidity and dissolved metal content that lasted a week. In this pulse, the acidity reached 307 mg/L CaCO3 and the total dissolved aluminium reached a maximum of 24 mg/L. Higher concentrations of dissolved metals may have been the cause for lower performance due to increased precipitation and coating on the limestone.

Jan 1, 2003

By David S. Yang

The Cement Deep Soil Mixing (CDSM) method introduces and mixes cementitious materials with in situ soils using hollow-stem rotating shafts equipped with a cutting tool at the tip and mixing paddles above the tip. CDSM generally produces a soil-cement panel consisting of three overlapping soil-cement columns. The soil-cement panel is then extended to form walls, which are effective for excavation support and groundwater control due to the continuity and low permeability of soil-cement walls. Two design approaches could be taken in the application of CDSM for excavation support: 1) single wall design and 2) gravity wall design. The former one is treated as a wall technology and the latter one is treated as a soil stabilization method. This paper will review the CDSM equipment and installation procedures for the construction of these two types of soil-cement walls. Four case examples are used to illustrate the design and application of these two types of soil-cement walls.

Jan 1, 2003

By Joseph B. Alberts, David D. DiPonio, Francis B. Manning

From 1996 to 2001, Wayne County and 13 suburban Detroit communities constructed the Downriver Regional Storage and Transport System (DRSTS) to improve area water quality, protect public health and alleviate basement flooding. The project consisted of a 10-mile long storage and transport tunnel, a pump station at the existing wastewater treatment plant, 9 miles of relief sewers (6 in tunnel and 3 in open cut). The work was separated into 10 contracts. Due to hydraulic design requirements and other constraints, the tunnel profile was located generally 65 feet below ground surface within a soft to medium clay strata which skimmed along the top of a very dense glacial till “hardpan” overlaying bedrock. Boulders within the tunnel bore were recognized as a significant, but indeterminate risk. This paper presents a case history of the owner’s contracting strategy for risk assumption and management of the boulder impacts on the project. Actual conditions encountered during construction and contractual adjustments made to address problems are reviewed, and recommendations for future contracts are included.

Jan 1, 2003

By S. Jiansheng, H. Nakayama, D. Lu, A. Wang

ABSTRACT: New techniques and methods for 3D geo-mechanical model test are presented in this paper. The new model material NIOS with high density and low cost; the so-called DPSS (Discrete Principal Stress Surface) loading concept, the loading and monitoring system for the generation of the 3D initial stress field of the model test, also the special techniques and apparatuses for modelling the excavation of caverns located deep inside the model material, are developed and introduced. By adopting those new techniques, a very large 3D geo-mechanical model test with high comparability for a newly designed underground powerhouse has been successfully fulfilled. Key Words: 3D model test, underground group caverns, excavation process modeling. ZUSAMMENFASSUNG: Neue Techniken und Methoden für 3D geomechanischen Modellversuch wurden in diesem Artikel vorgestellt. Ein neues Modellmaterial mit hocher Dichte und niedrigem Preis, ein sogenanntes DPSS (Discrete principal stress surface) Ladenkonzept, ein Laden- und Überwachungssystem für die Erzeugung des 3D primären Spannungsfelds und überdies spezielle Techniken und Maschinen für das Ausbruch der tief in dem Versuchsmodell liegenden Kaverne wurden entwickelt. Bei Anwendungen dieser neuen entwickelten Techniken wurde ein sehr großer 3D Modellversuch mit großem Maßstab für ein geplantes unterirdisches Kraftwerk erfolgreich durchgeführt. Stichworte: 3D Modellversuch, unterirdischen Gruppekaverne, Ausbruchsmodellierung Résumé: le test de modèl de Nouvelles techniques et méthodes pour la géo-mécanique 3D est figuré dans ce papier. Le nouveau modèle de matériels NIOS avec la haute densité et le coût bas; la conception proposée de chargement DPSS (Discrete Principal Stress Surface), le système de chargement et de moniteur pour la génération de champs de stress initial du test de modèle, ainsi que les techniques et appareils spéciaux pour modeler les excavations de cavernes profondément localisées dans l’intérieur du matériel de modèle, sont développés et introduits. A travers l’adoptation de ces nouveaux techniques, le test de modèle de la géo-mécanique très large 3D avec la haute comparabilité pour actualiser une nouvelle étude de la centrale électrique sous-terraine a déjà accompli avec succès. Mots de clé: test de modèle 3D, groupes de cavernes sous-terraines, processus de modèle d’excavation

Jan 1, 2003

By G. Potts, K. Raiber, T. BoBo

Effective control of balling line circuits is a problem taconite companies have been dealing with for over thirty years. The sensitivity of balling circuits to changes in moisture, bentonite, concentrate particle size, and other operating parameters are the main reasons for control problems. This paper presents test results and describes the integration of existing instrumentation with a digital image analysis system on a balling circuit. This work has the goal of developing control strategies to automatically adjust water spray and bentonite addition, to optimize the size distribution on the roll screen and reduce the variability in control between balling attendants, resulting in more consistent greenball product quality.

Jan 1, 2003