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By J. F. Papp

In the United States, chromium has been consumed in three major markets: chemical, metallurgical, and refractory. The predominant end use for chromium in the United States is in the metallurgical market as an alloying element in the production of stainless steel. In addition to being a major stainless steel-producing country, the United States is a major world producer of chromium-containing chemicals and has used substantial amounts of chromite ore for refractory applications. Chromium use is not easily further subdivided within the chemical and refractory industries because there is insufficient publicly available information to do so; however, chromium use can be subdivided among metallurgical industry uses based on the American Iron and Steel Institute (AISI) reported shipments of stainless steel by market classification (agricultural, aircraft, automotive, etc.). It is the goal of this study to determine the distribution of U.S. chromium apparent consumption among major markets in the United States. The distribution is expressed in the form of dimensionless fractions that are computed based on documented chromium consumption by major market. The distribution of chromium among markets within the metallurgical market is computed in a similar manner. Distribution factors are first computed for the major markets, then for markets that are subdivisions of the metallurgical market. The distribution of chromium among major markets has changed substantially over the time period of analysis. The fraction of chromium consumed by the metallurgical market has increased while that of the chemical and refractory markets has declined. Within the metallurgical market, the service industry market accounts for the greatest fraction of chromium consumption followed by transportation. Electrical, machinery, and fabricated products markets account for a substantial share of the metallurgical chromium consumption.

Jan 1, 2004

By Gift Makusha, Dave Minney

Anglo Coal South Africa mines coal for both the domestic and export market using open cast and strip mining methods. To establish a mine, a process is set in place to gather ever increasing amounts of geological and metallurgical data to confirm a proven reserve. Increasingly, geotechnical data are also included in this process to confirm that reserve is easily and safely mineable. The mine design process is an iterative one using a combination of numerical modelling and empirical data to arrive at a mining layout that is both, practical, productive and safe. In South Africa it is a legal requirement to compile a code of practice to combat rock fall and slope instability accidents and these have to be revised annually, reinforcing the iterative process of continual improvement. To ensure best practise occurs, all Anglo Coal operations are subjected to annual 2nd party audits and ad hoc 3rd party audit by independent consultants. This paper attempts to explain the process described above in a concise, but understandable manner. 1.0 GEOLOGICAL SETTING The Ecca sediments date from the Permian period and the coal deposits were formed in glaciated valleys on a basement of Dolomite, Ryolite or Granophyre rock types. The sediments overlying the coal deposits are typically flat lying and multiple bedded. The sediments consist of mudstones, shales and sandstones and are generally capable of forming stable highwalls given the time that they must stand up for. Anglo Coal extracts coal from the Witbank, Highveld and Vereeniging coalfields. The Witbank coalfields contain five seams numbered from the base upwards, 1 to 5 Seam; Highveld coalfield the 2 and 4 Seam and the Vereening area the seams are described as Top, Middle and Bottom seams. Coal deposited over the basement Dolomite formation display very erratic dips, as contemporaneous subsidence occurred in some instances over sinkholes that were forming, resulting in local thickening of the coal deposit and resulting in strata that dips toward the centre of the sinkhole.

Jan 1, 2006

By Z. Konstantinovic, M. Ahrens

Due to the large installed electrical power and the large number of electric drives in minerals and mining plants power factor compensation and harmonic filtering has always been an important issue. For the design of harmonic filter and power factor compensation installations several approaches can be taken. The paper describes different concepts and their advantages and analyzes special requirements and design considerations for minerals and mining plants. It also highlights areas where problems can occur and which points need to be addressed carefully. Optimized designs and solutions are discussed in case studies and the resulting energy savings and benefits for the plant operation are shown.

Jan 1, 2007

By Joel Moskowitz

A new office complex is being constructed within 25m of the Hudson River in New Jersey. The project, about 140 m by 100 m, will include 4 basements under the entire footprint. The perimeter was to be secured by a 0.8 m thick diaphragm wall, laterally supported by high capacity tieback anchors to rock. Columns were to be supported on footings or piers to rock at a nominal bearing pressure of 3.8 MPa at depths up to 17m. Although some variation in rock quality was observed in borings, a substantial vertical seam of weathered and/or decomposed rock, 1 to 2 meters wide by as much as 8 meters deep, was encountered during construction necessitating field redesign. In some locations the seam dipped below more competent rock. Footings were redesigned for support on drilled caissons, or soft rock was excavated and replaced with concrete necessitating a reduction in bearing pressure of the footings by one half.

Jan 1, 2002

The ability to optimise a concentrator from mill feed to final products requires a simulator which integrates comminution, classification and separation modelling. In order to model this range of processes, such a simulator must handle a variety of information about the ore. The AMIRA P9 project has developed a whole-of-concentrator simulation capability which brings together a texture-based model of mineral liberation, quantitative X-ray micro-tomography analysis to measure the inputs required by this model, and a multi-component simulator software framework. In the context of this approach, the term ?multi-component? implies the ability of the simulation to handle many particle properties simultaneously; for example size, composition, density, floatability etc. The simulation software framework provides the means to manage the flow of data around a circuit flowsheet, allowing each process model to access the information relevant to that particular model. A case study based on plant data from a gold-bearing pyrite concentrator is used to demonstrate the capabilities of the multi-component approach in simulating circuits which contain comminution and separation processes.

Feb 27, 2013

The New Zealand Minerals Industry is small but growing. Over the next 10 years it will be facing stiff international competition for skills to support this growth, particularly from Australia who are forecasting that a further 70 000 people will be employed by 2015.   The value of commodities mined and quarried in NZ continues to increase; and the value of coal, metals and industrial minerals production reached $1.505 billion in 2006, an increase of 15 per cent on 2005. Production increases will continue à. Latest Crown Minerals statistics show that national prospecting and exploration expenditure rose to $29.9 million in the year ended March 31 2006 û an increase of 46 per cent from the $20.4 million spent in the March 2005 year. The equivalent 2001 year expenditure was only $2.48 million.   The industry already experiences difficulty in recruiting the people it needs with ongoing demand for skilled underground miners, trades people, and mining professionals. This discussion paper will outline the national context with regard to labour, skills and training. It will suggest options and provide an opportunity for conference participants to discuss the way forward.

Jan 1, 2007

By C. Balci

Specific energy is defined as the amount of work required to break a unit volume of rock and is used to predict the performance of mechanical miners. It is obtained from full-scale rock cutting experiments, which require large block samples, experienced personnel and expensive equipment found in only a few research centres in the world. Estimation of the optimum specific energy, at which a given geological formation is excavated at optimum cutting geometry in the most energy efficient manner, from mechanical rock properties to predict the performance/efficiency of roadheaders is the basic aim of this study. The mechanical rock property tests require only core samples, which are easier to obtain and to test. In this context, full-scale rock cutting tests are performed on 23 different rock, mineral and ore samples including sandstone, claystone, tuffite, chromite, trona and copper collected from some operating mines in Turkey. The optimum specific energy values are obtained for each sample. Physical and mechanical property tests are performed on the core samples obtained from the same samples to determine uniaxial compressive strength, indirect (Brazilian) tensile strength, static and dynamic elasticity moduli, Schmidt hammer rebound values, density, and Cerchar abrasivity index. The relationships between the optimum specific energy and the mechanical rock properties are analysed using statistical methods. The results indicate strong relationships between the optimum specific energy and the mechanical rock properties. The strongest relationships are found by using uniaxial compressive strength and tensile strength. The performance models developed in this study are in good agreement with the empirical models previously developed for roadheaders and can be used reliably for prediction purposes. Keywords: Mechanical excavation, roadheader, performance prediction, rock cutting, optimum specific energy, mechanical properties of rocks.

Jan 1, 2004

By K. Aoki, Y. Mito, S. Shirasagi

The authors developed the TBM Excavation Control System (the TBM Navigator), in order to realize the advanced observational construction. During the excavation using this system, the rock strength value is immediately calculated from the TBM driving data as an index of rock properties, and the drill energy coefficient is also calculated from the drill logging data that is carried out using the probe hole ahead of the tunnel face. In this study, a new, geostatistical simulation-based method is proposed for the automatic prediction of the rock properties ahead of the tunnel face with good precision, using both the drill logging data and the TBM driving data. The applicability of this method is validated through the prediction at the actual tunnel excavation that passes through the faults. Les auteurs ont mis au point un Système de Contrôle de forage avec la machine à pleine section (Navigateur de la machine à pleine section), en vue de réaliser un système de surveillance plus efficace. Avec ce système, la résistance de la roche est immédiatement calculée, au cours du forage, à partir des données de conduite de la machine, comme indice des propriétés de la roche, et le coefficient d'énergie de la foreuse est également calculé à partir des données de log de forage collectées dans un trou de sonde foré dans le front de taille. Dans cette étude, on propose une nouvelle méthode basée sur la simulation géostatistique qui permet de prévoir d’une manière automatique, des propriétés de roches se trouvant derrière le front de taille avec une précision satisfaisante, à l’aide des données de log de forage et celles de conduite de la machine à pleine section. Cette méthode s’est avérée suffisamment précise au cours du forage d’un tunnel réel qui traversait une zone de failles. Die Autoren entwickelten das TBM Ausschachtungssteuerungssystem (den TBM Navigator), um noch besser überwachte Bauarbeiten zu ermöglichen. Unter Einsatz dieses Systems wird die Gesteinsfestigkeit während der Ausschachtungsarbeiten unmittelbar aus den TBM Antriebsdaten als ein Index für die Gesteinseigenschaften berechnet. Gleichzeitig wird auch der Bohrenergiekoeffizient aus den Bohrlogdaten berechnet, die an Hand der Probebohrung am Stirnende des Tunnels erhalten wurden. In der vorliegenden Studie wurde ein neuartiges, auf geostatistischen Methoden basierendes Verfahren für die automatische und angemessen genaue Vorhersage der Gesteinseigenschaften am Stirnende des Tunnels vorgeschlagen, für das sowohl die Bohrlogdaten als auch die TBM Antriebsdaten verwendet werden. Die Anwendbarkeit dieser Methode wird durch die Vorhersage bei einer tatsächlichen, durch Verwerfungen verlaufenden Tunnelausschachtung bewiesen.

Jan 1, 2003

By S. Banisi, M. Poorkani

The Sarcheshmeh copper deposit contains 1 billion tones of ore averaging 0.7% copper and 0.025% molybdenum. It is located southeast of Iran and currently processes 41,000t/d. Molybdenite as a by-product is recovered in two separate stages. First, a bulk coppermolybdenum concentrate is produced and in the second stage these two are separated. The recovery of molybdenite in the first and second stages is 65% and 85-90%, respectively. The yearly production of molybdenite concentrate varies between 3500 and 4000 t. Sodium sulphide is used as the depressant of the copper and iron bearing minerals which due to a rather high consumption (17.7 kg/t) constitutes one of the major cost items of the plant (i.e., 58% of total reagents cost). A detailed laboratory scale study showed that replacing air with nitrogen could reduce the consumption of sodium sulphide (i.e., H2S or mineral origin). Nitrogen for the plant was supplied from an oxygen plant used for the smelter through a 1400 m long pipeline. The existence of the oxygen plant at the Sarcheshmeh complex was a key factor in the implementation and success of this project. After using nitrogen in the plant for a period of twenty one months, the consumption of sodium sulphide was reduced from 17.7 to 14.2 kg/t at constant metallurgy. The reduction was lower than expected which was mainly due to the type of sodium sulphide used and the lack of any automatic instrument to control the depressant (sodium sulphide) dosage. The latter in turn caused the operators to overuse sodium sulphide in order to reach and maintain the target metallurgy (i.e., higher molybdenite recovery along with lower copper content of the concentrate).

Jan 1, 2005

By Jeffrey M. Listak

The National Institute for Occupational Safety and Health (NIOSH) conducted field tests to evaluate the effectiveness of a wet head continuous mining machine for reducing dust exposure for continuous miner operators. Wet head technology delivers water via sprays to the continuous miner's cutter head as opposed to traditional standard sprays located on the boom and body of the mining machine. The sprays, positioned directly behind each bit on the cutter head, deliver water at the point of attack, serving to cool the bits during mining to reduce the potential for frictional ignitions. The sprays also flood the coal with water to potentially suppress dust generation. Dust surveys were conducted at several mines to evaluate the wet head's effectiveness to control respirable dust exposure at the continuous miner operator location and in the immediate return. Results show that the wet head miner improved air quality at both locations to varying degrees in some cases and not in others when compared to a continuous miner with a standard spray system.

Jan 1, 2010

By Susan L. Bednarz

Recent advances in digital cameras and image processing allow photographers to produce excellent high-resolution action shots in low light and high contrast conditions commonly encountered underground. Digital photography is often used for construction and inspection documentation for underground structures. Designers, owners, and contractors benefit from quality photographs that document incremental progress and project milestones. Documentation photos serve as a lasting record of as-built conditions, are an important marketing tool, and help the owner build public support for expensive public works projects. When the project is complete, the only mementos that the participants will hold onto are the photographs.

Jan 1, 2008

By Diego Canez Fernandes, Henriquison Bottrel Reis, Mauricio Covcevich Bagatini

As técnicas que visam aumentar a densidade de carga possibilitam elevar a produtividade da coqueria e, além disso, permitem utilizar carvões com menor poder coqueificante. O aumento de densidade pode contribuir ainda para a obtenção de um coque de melhor qualidade, o que contribui para a redução do coke rate no alto-forno. Uma alternativa para aumentar a densidade de carga é a adição de óleo na mistura de carvões, o que reduz a tensão superficial da água, permitindo uma maior aproximação entre as partículas e favorecendo o contato efetivo durante a fase plástica. Neste contexto, o presente trabalho teve como objetivo avaliar o efeito da adição de óleo na densidade de carga para diferentes condições de granulometria e umidade do carvão empregado. Para isso foram realizados ensaios para medir a densidade de carga em três níveis de umidade (8%, 10% e 12%) e granulometria (82%, 85% e 88% < 2,83 mm). Posteriormente, foram realizados ensaios de coqueificação em escala piloto, e o coque produzido foi avaliado quanto ao DI15/150 (drum index), CRI (coke reactivity index) e CSR (coke strenght reaction). Os resultados mostraram que a adição gradativa de óleo promoveu aumento na densidade de carga enquanto a elevação da umidade do carvão e seu afinamento provocou a redução desse parâmetro. A qualidade metalúrgica do coque aumentou com a elevação da densidade de carga demostrando que essa é uma técnica com potencial de uso em plantas industriais.

Oct 1, 2019

By G. Deissman, S. Kistinger

For the last 15 years environmental Life-Cycle Assessments (LCA) have increasingly been used to evaluate the environmental performance of industrial processes and products and have been employed as a basis in decision making processes in the public and industrial sector. However, assessment methodologies for environmental protection measures and reclamation/remediation measures with respect to their consumption of natural resources are generally poorly developed. In this presentation a methodology for LCA of environmental protection measures and remedial actions, respectively is suggested, using the remediation/reclamation of mining sites as an example. Key aspect of this approach is the development of an evaluation method appropriate for environmental protection measures, which links the various impact indicators recognised in the impact assessments and allows their integrated assessment.

Jan 1, 2005

By Ren G. Dong, Richard McCormick, Dan E. Welcome

Vibration exposure at workplaces is generally multi-axial. The health effects of vibration exposure also likely depend on the vibration direction. Therefore, there is a wide interest in the simulation of multi-axial vibration in laboratory experiments. Advances in technology have led to the development of a new 3-D test system for studying hand-transmitted vibration exposure and health effects. The purposes of this paper are to introduce the system and to present the results of its preliminary evaluations. Test System As shown in Figure 1, the system is basically composed of three vibration generators, a multi-axis vibration control system, instrumented handle, handle fixture, and shaker-fixture linkages (stingers). [ ] Figure 2 shows the array of three vibration generators (MB Dynamics, Energizer BLACK-500 lbs) and their associated support bases and foundation developed by MB Dynamics (Cleveland, USA), which create the 3-axis simultaneous motion. These electrodynamic exciters are powered by power amplifiers which provide current proportional to the analog drive signal from a controller. The controller (JAGUAR Multi-Input/Multi-Output closed-loop vibration controller) was provided by Spectral Dynamics, San Jose, California, USA). NIOSH-designed instrumented handle was equipped on the system.

Jan 6, 2006

Membrane technology has been available for over 36 years, but has been used sparingly in the general mining industry. However, recent developments in polymer chemistry, spiral wound element construction, pretreatment equipment and techniques and an expanded understanding of membrane fouling and cleaning techniques have dramatically improved the reliability and robustness of membrane based systems in the mining industry. Harrison Western has expanded the use of this “new” technology to enhance the use of membrane technologies to separate metals from large volume heap leach mining solutions containing copper, zinc, and iron, gold or silver. Moreover, membrane technologies are ideally suited to fractionations that add value to processing fluids from refineries like separating metals from acids or concentrating acids and producing high quality process fluids. Finally, wastewater from Acid Mine Drainage (AMD) or, as in the case of the Newmont Yanacocha Mine in Peru, the treatment of excess barren leach solution created during the rainy season, can be cost effectively processed to meet World Bank Standards for surface discharge. Polymeric membranes, specifically thin-film composites, have been developed that will purify, fractionate or concentrate gold, silver, copper, zinc or nickel. Recent applications have been developed for spiral wound modules that operate across the pH spectrum from 0 to 14. Systems using membranes have been constructed that operate on feed streams from 140° C to 300 centipoise. Opportunities exist to apply membrane technology to concentrate gold, silver, copper, zinc or nickel using thin film composite membranes. Engineered membrane types can operate across the spectrum from low pH (<2) acid applications to high pH > 10 cyanide applications. Incorporating HW EMS™ membrane technologies into current mining operations could allow one to increase production because the membrane technology would be used to pre-concentrate heap leach solutions, and therefore, increase utilization of existing extraction and refinery capabilities.

Jan 1, 2007

By E. De Souza

Two comprehensive surveys, which focus upon backfill practices and the economics of backfilling in underground mines in Canada, have been conducted. The two surveys were designed to assess operational practices and costs associated with the wide scope of filling operations that must be met by individual mines, ranging from raw material feed to the preparation plant, through underground backfill transportation, to in-stope product placement. This paper presents the current state of backfill usage in Canada, identifies trends in minefill practices and provides mine operators with an updated database of information upon which they might compare their own practices and costs with present trends throughout the industry.

May 1, 2003

By Y. Luo

Cuando se diseña y operan minas de carbón subterráneas con el método de cámaras y pilares, es siempre difícil obtener un buen equilibrio entre la prevención de subsidencia de la superficie y la obtención de un alto coeficiente de recuperación. En este trabajo se propone una metodología de diseño aplicando la teoría de arco de presión y se detallan los principios y modelos matemáticos involucrados. Se desarrolló un programa de computadora a fin de realizar el proceso de optimización del diseño y fue aplicado a la examinación de un caso documentado en el que había sucedido una falla masiva de un pilar en cascada sobre un área grande en una mina de carbón poco profunda. Los resultados indican que el método de diseño propuesto puede ser aplicado para prevenir la subsidencia y a la vez obtener un alto coeficiente de recuperación para operaciones mineras de cámara y pilares.

Jan 1, 2014

By N Clarke, R Dineen, W Jones

The Mt Lyell copper mine in western Tasmania has discharged acid drainage (AD) into the Queen and King Rivers and Macquarie Harbour for over a century. Presently, dissolved copper loads of about 1000 tonnes per annum and dissolved aluminium loads of >2000 tonnes per annum are contained in the AD, which is derived from underground workings (~60 per cent) and historic waste rock dumps (~40 per cent). Flows vary from about 100 L/s during dry periods, to >400 L/s during the wet winter. The site is presently operated by Copper Mines of Tasmania (CMT) who are not responsible for the acid drainage generated from the mine site. Although western Tasmania is famous for its mining history, tourism and aquaculture have emerged as the new industries on the West Coast, with a major tourism railway (the Abt) recently opened along the banks of the Queen and King Rivers. The emergence of these industries in a æclean greenÆ Tasmania has resulted in a strong community and government push to remediate the acid drainage. Remediation investigations and efforts at Mt Lyell were initiated by the Department of Primary Industries, Water and Environment (DPIWE), previously known as DELM, in 1995, and have included the quantification of environmental impacts arising from the AD, and the investigation and costing of potential remediation options. A primary focus of the work has been to identify cost-neutral options which recover metals from the AD in a saleable form to help defray on going treatment costs. This paper summarises these activities in generally a chronological order, highlighting findings of the program that are potentially applicable to other acid drainage sites.

Jan 1, 2003

By Carlos Dellepiane, Jorge Arizaca

La máquina Box Hole, está diseñada para realizar perforaciones ciegas, positivas y con inclinaciones exigentes, las cuales no son posibles con productos similares en el mercado. Los sistemas de propulsión autónoma y operación están integrados en la misma unidad, lo cual permite un fácil desplazamiento hacia las galerías, también un posicionamiento rápido. Otra de las ventajas importantes es que, no necesita una losa de concreto para el anclaje de la máquina al terreno. El avance teórico de perforación de la máquina Box Hole es de 1 m/h, el avance de perforación obtenido en campo ha sido de hasta de 1.2 m/h, superando en 20% las expectativas de diseño.

Sep 30, 2022

By M. H. Weinecke, B. P. Faulkner

This paper will discuss the process for making lightweight aggregate, the waste materials that make good lightweight aggregate, the chemistry of making lightweight aggregate and finally a discussion of the commercial prospects for making lightweight aggregate from wastes. Svedala Industries has been making lightweight aggregate (LWA) from waste materials for the last ten years. Many clay-like materials, such as coal-fired boiler ash and washings from a granite quarry, can be used alone or with additional waste materials to produce a commercially saleable LWA.

Jan 1, 2001