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By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

One way to upgrade iron ore is to process it into pellets. The pelletizing process is multifaceted, involving complex fluid dynamics with highly turbulent, high-temperature flow in intricate geometries. This makes it hard to perform measurements during operation, so a useful tool for better process understanding is computational fluid dynamics (CFD), where the challenge is to perform efficient and trustful simulations of complicated problems. A validated simulation model can be valuable for increased process control and development. In this paper, the flow field and coal combustion process in a pilot-scale iron-ore pelletizing kiln is simulated using a CFD model. The objective of this work is to apply a coal combustion model to enable an investigation of thermal effects from the flame on the surrounding flow field.

By Marie-Josée Banwell, Cyriac Sebastian, Giacomo Falorni, Sara Del Conte

Interferometric Synthetic Aperture Radar (InSAR) is a satellite-based monitoring technique that complements other in-situ methods for detecting and measuring surface displacement. Recent advances in data processing algorithms, coupled with the use of high-resolution satellite systems, make it possible to now provide high-frequency InSAR monitoring services, with updated results delivered every time a new satellite image is acquired. The advent of large, continuously updated data sets, however, brings new challenges, including the need to rapidly sift through the data to identify only those points showing relevant ground displacement information. This has been achieved by using trend variation analysis tools, that quickly isolate and highlight only areas of anomalous behavior. The paper focuses on project case studies where continuous InSAR monitoring has proven to be key in identifying displacement trend changes near tunnel alignments.

Jun 13, 2021

By V. Karra, G. Beerkircher

Application of the innovative WaterFlush® crushing technology to the processing of gold, copper, and iron ores is presented for retrofit circuits and productivity gain in each case is stated. New operations containing WaterFlush are described in brief.

Jan 1, 1995

By Ronald Allum

Underground copper mining at Magma Copper Company's San Manuel Mine has been un going since 1955. The block caving mine has been producing copper ore at the rate of over 16 million tons per year. Depressed market conditions during the 1980's forced Magma to look at new technology. Late in 1984, Magma began testing new equipment and mining methods at the underground mine at San Manuel, Arizona. The tests resulted in a move towards mechanized production using new procedures and equipment. The goal was to increase efficiency and cut costs through mechanization.

Jan 1, 1988

By C. Roos

Traditionally within the mining industry, the main functional process flow for resource and reserve evaluation proceeds from geologists who build the geological model, to resource estimation geologists (modelers) who estimate the grades, to mining engineers who develop the mine design and schedule. The interface between these three disciplines is not always seamless. Assumptions made during one stage of the process are not always communicated down the line, even though most mining companies have procedures in place to encourage communication across the various disciplines. These procedures do not always achieve their aim due to a variety of reasons including time constraints, appropriate people not being available, or a lack of understanding of what other disciplines require, and the handover process can degenerate into one of sending computer files on to the next discipline in the process flow. This paper focuses on the interface between the resource estimation and mine engineering disciplines, and outlines some of the common assumptions made when generating a resource model and the risks that engineers may be taking when elevating cutoff grades, optimizing schedules or generating forecasts. The case studies presented focus on openpit gold deposits, but the concepts should be applicable throughout the industry. A summary of key questions and recommendations is provided.

Jan 1, 2014

By Svante Lundbrink

A new generation hydraulic rock drill featuring more than 50 percent higher performance than other drills has been introduced by Atlas Copco. In conjunction with the new rock drill, control systems have developed and refined to handle the higher drilling output, and to maintain an acceptable service life of drill string components. These improved features are built into the Rocket Boomer, a new high-performance drill rig, used at the recently completed Hanging Lake project in Colorado. Experiences from this project will be reported together with results from a highway tunnel construction project in Italy.

Jan 1, 1991

By J. Morris, R. Sellaro

Petro-diesel is a common collector for coal flotation, but the partitioning of diesel range organics (DROs) in process streams has not been widely studied. Preliminary research suggested that under normal dosing schemes total residual DRO contents in process waters should be limited to the sub-ppm water-soluble fraction (WSF). Further, polycyclic aromatic hydrocarbons (PAHs) should partition proportionately with DROs. The purpose of this study was to confirm these findings in laboratory flotation tests. Total DRO and specific PAH contents were measured in the waters associated with the concentrate and tailings streams. The results show that concentrate waters consistently had higher amounts of DROs than tailing waters. Moreover, the DRO contents in both streams generally increased with increasing diesel dosage. In line with preliminary research, DROs appeared to be limited to the WSF, and PAHs tended to partition proportionately with DROs. Under typical operating conditions, it appears that residual DROs should not present an environmental concern, but conditions should be avoided that allow significant overdosing of diesel.

Jan 1, 2014

By Tom Plouf, Deepak Malhotra

INTRODUCTION The U. S. mining industry experienced a severe recession in the early 1980's. This resulted in the realization that the domestic mining industry had to compete on a global basis and only the strong or the low-cost producers would survive. The economic viability of a mining company not only depended on maximizing mineral recovery but also on its ability to do so at minimum cost. Companies had to become more productive not only by cutting costs, but also by developing and/or evaluating new technologies in existing or new plants. Several innovative concepts, including in-pit crushing and conveying, fine crushing, improved classification equipment, flotation, column flotation, pressure filtration, etc., have been developed in recent years. This paper addresses the impact of new flotation concepts and equipment on mill design. MILL DESIGN PHILOSOPHY Modern mill design, especially for large capacity plants, has its foundation in minimizing capital and operating costs. Capital costs can be minimized by minimizing the various components of the capital cost: infrastructure, equipment, instrumentation, structural, initial spare parts costs, etc. All these costs are minimized by simplifying the mill design and/or process flowsheet. The simplified process flowsheet, where applicable, consists of a single stage primary crusher followed by a semiautogeneous - ball mill grinding circuit to produce feed for a flotation circuit. Multiple flotation circuits have been eliminated in most cases. These concepts minimize the cost and encourage the use of large capacity equipment while maintaining optimum metallurgical recovery. The philosophy of mill modernization/modification is generally driven by the desire to increase the mill capacity within the limits of the existing mill building. This need is facilitated by using large size flotation equipment and eliminating multiple parallel flotation circuits in order to minimize capital and operating costs. Conventional flotation machine development has paralleled this mill design philosophy. FLOTATION CELL DESIGN Since froth flotation has been the most widely used separation process for over half a century, one would expect that it would be possible to design and select flotation machines for specific applications based on scientific principles. But this has not been the case. Best judgment, experience and personal prejudice have played a key role in equipment selection. These factors, along with the difficulty of evaluating new concepts in commercial plants, has slowed progress in implementation and commercialization of innovative ideas and/or equipment. Conventional Flotation There have been no major technological advances in conventional flotation cell design in recent years. A recent flotation cell survey indicates that 'larger flotation cells are still the order of the day.”(1) A comprehensive review of design of flotation machines indicate that they have been mechanically redesigned and are generally simpler and easier to maintain and less expensive to manufacture. (2,3) The approximate chronological development of conventional cells from the 25 cubic foot cells to the 3000 cubic foot cells, which were recently installed at the Copperton concentrator of Utah Copper, is given in Table 1. Larger flotation cells are the obvious choice for new plants or plants looking for expansion because of the following reasons: • They have lower capital cost per unit volume • Installation costs are generally lower because fewer units require less space • Maintenance costs are lower because of fewer mechanisms • Power requirements (HP/ton dry feed) are generally lower • with increased flotation cell size as illustrated in Table 2 [Table 1. Conventional Flotation Cell Size Development Year Individual Cubic Cell Size, Feet 1925 25 1935 50 1960 100 1965 300 1970 500 1975 1,000 1980 1,500 1985 3,000]

Jan 1, 1989

By C. Roos

Tradicionalmente en la industria minera, el flujo principal del proceso funcional para la evaluación de recursos y reservas procede de geólogos que elaboran el modelo geológico, de allí a los geólogos que hacen la estimación de los recursos (los modeladores) quienes estiman los grados, y a los ingenieros de mina que desarrollan el diseño de la mina y su calendario. La interfaz entre estas tres disciplinas no está siempre exenta de baches. Las presunciones hechas durante una etapa del proceso no siempre son comunicadas a los demás, a pesar que la mayoría de las empresas mineras tienen procedimientos y protocolos establecidos para promover la comunicación a lo largo de las distintas disciplinas. Estos procedimientos no siempre logran su propósito debido a una variedad de razones que incluyen restricciones de tiempo, no tener disponible a las personas apropiadas, o a una falta de entendimiento de lo que las otras disciplinas requieren, y el proceso de traspaso puede degenerar en el envío de archivos a la siguiente disciplina en el flujo de proceso. Este artículo se ocupa de la interfaz entre la estimación del recurso y las disciplinas de la ingeniería de minas y el esquema de algunas de las presunciones comunes hechas al generar un modelo del recurso y los riesgos que los ingenieros podrían correr al elevar los grados de corte, optimizar calendarios o realizar predicciones. Los casos de estudio presentados se centran en depósitos de oro a cielo abierto, pero los conceptos deben ser aplicables a toda la industria. Aquí también proveemos un resumen de preguntas clave y recomendaciones.

Jan 1, 2014

By Robert Dunne, John Angove

The physical properties of an ore body require determination for virtually all mining projects, new and existing. The extent and regularity of such determinations being subject to the size and homogeneity of the orebody. Such properties have an impact at the design stage of new plants, with respect to equipment specification, and thus effects capital costs; and also impacts on the operating costs of new and existing plants, with respect to power consumption, production levels and part replacements. All of these can severely alter the bottom line and can be the determining factor in the economic viability of many projects. This paper examines some of the most common properties that are measured, the procedures utilised in determining these properties, and their variability under conditions of reproducibil­ity, and to a lesser extent repeatability. The properties looked at were Impact Crushing Work Index, Abrasion Index, Bond Rod Mill Work Index and Bond Ball Mill Work Index. A number of testing laboratories throughout Australia and the US were utilised in the survey. The results showed up some interesting and important features of the procedures used, all of which have become accepted industry standards, and which had varying effects on the final result. Tests such as the rod and ball mill indices would appear to have reasonably robust procedures which allowed for the determinations of the respective index without the introduction of significant variations, although there were indications that variations could occur. The other tests gave a sufficiently different picture to be able to suggest that an argument could be made for a more intensive investigation to be undertaken, with the possible outcome that a modified test procedure or an alternative test is required.

Jan 1, 1997

By A. C. Nixon, A. D. S. Gillies, Hsin Wei Wu

Ventilation and refrigeration strategies for the 3000/3500 orebodies, Mount Isa Mines, Australia were reviewed. The orebodies lie between 1,200 and 1,800 m below surface and are characterised by steep geothermal gradients, intensively mechanised stoping methods and high ambient air temperatures in summer. Providing acceptable working conditions under these situations is difficult and costly. The ventilation air quantity required in the 3000/3500 orebodies exceeds 550 m3/s when the production rate is greater than 2.5 million tonnes per year. The maximum quantity that can be supplied and exhausted using the existing intake and return ventilation system is estimated at about 630 m3/s. For production rates greater than 3 million tonnes per year, either new intake and return airways will need to be developed or innovative approaches such as controlled partial recirculation used. A description is given of technical and economic investigations conducted at Mount Isa into controlled partial recirculation. During these investigations, a major field trial of a controlled partial recirculation system was undertaken with results indicating that an acceptable working environment can be achieved practically and economically utilising this approach. The cost involved in controlled partial recirculation for supplying the required ventilation quantity when the production of 3000/3500 orebodies exceeds 3 million tonnes per year is examined. A cost comparison between recirculation and other conventional alternatives such as new surface shaft or underground booster fans is included. The results indicate that the option of a new surface shaft will incur a high initial capital cost and moderate annual operating costs. The alternative of underground booster fans will necessitate a moderate capital cost and very high operating costs. Controlled partial recirculation, in this case, offers both the lowest capital and operating costs of the three options evaluated.

Jan 1, 1995

By Stuart M. Lipofsky, Norm Hutchins

The Metropolitan Water District of Southern California has undertaken the Lake Mathews Outlet Facilities project to replace the existing outlet facilities. In the late1990s, consulting engineers for the District determined that the Lake Mathews Outlet Facilities were susceptible to a catastrophic failure during a seismic event. To ensure a reliable supply of water to Metropolitan’s customers in the Los Angeles area, the District decided to construct new outlet facilities. This Project consists of excavating a large diameter junction shaft, a 6.10 m (20 ft.) horseshoe tunnel, three short 4.88 m(16 ft.) horseshoe bypass tunnels, and a large excavation within a cofferdam that were all driven in difficult rock conditions. Additionally, a new concrete outlet tower was constructed and connected to the existing tunnel by the new bypass tunnels and through the junction shaft. The J.F. Shea Co., Inc. of Walnut, California, is currently finishing the construction of the Lake Mathews Outlet Facilities Project for Metropolitan. The large diameter junction shaft is 50.60 m (166 ft.) deep, excavated 16.15 m (52 ft.) in diameter and lined with a61 cm (2´-0?) thick steel reinforced concrete lining to a finished diameter of 14.63 m (48ft.). The shaft was excavated full face with one stationary shaft three-boom jumbo, modified for the large diameter. The shaft also consists of four sets of gate guides extruding from the shaft wall towards the center of the shaft that provide the ability to operate up to four mechanical gates at any time, to open or close each tunnel. This paper will present the junction shaft excavation and concrete construction techniques, including the innovative slip form method utilized to construct the junction shaft.

Jan 1, 2003

By J. Morris, R. Sellaro

El petrodiesel es un colector común para la flotación de carbón, pero la partición de compuestos orgánicos de diesel (DRO por sus siglas en inglés) en corrientes de proceso no ha sido ampliamente estudiada. Investigaciones preliminares sugieren que bajo esquemas de dosificación normales los contenidos residuales totales de DRO en aguas de procesos deben estar limitados a la fracción soluble en agua (WSF por sus siglas en inglés) sub-ppm. Es más, los hidrocarburos aromáticos poli-cíclicos (PAH por sus siglas en inglés) debería segmentarse de manera proporcional con los compuestos orgánicos de diesel (DRO). El propósito de este estudio fue confirmar estos resultados en pruebas de flotación realizadas en laboratorio. Se midieron los contenidos totales de DRO Y PAH en aguas asociadas con los flujos o corrientes de concentrados y relaves. Los resultados muestran que las aguas con concentrados tenían de manera consistente mayores cantidades de DRO que las aguas de relaves. Es más, los contenidos de DRO en ambos flujos generalmente se incrementaban con el aumento de la dosis de diesel. De acuerdo con la investigación preliminar, los DRO parecían estar limitados a la fracción soluble en agua (WSF) y los PAH tendían a segmentarse proporcionalmente con los DRO. Bajo condiciones de operación típicas, los DRO residuales no deberían representar una preocupación medioambiental, pero deben evitarse situaciones que permitan una sobredosis significativa de diesel.

Jan 1, 2014

By M. Nambiar

Due to the remote locations of mining projects and the need for long transmission lines to provide electrical power, mining sites often operate with poor network power quality and low short-circuit capacity. To cope with this situation, more and more mining operators are considering the installation of appropriately designed synchronous condensers together with power factor correction and harmonic filter systems (PFC & HFS). The installation of such power quality equipment is viewed as a technological advancement in the mining application. An adequate level of short-circuit power is essential and has to be ensured for the safe and reliable operation of especially large cycloconverter-driven gearless mill drive systems (GMDs) used for grinding. This paper explores the impact, technical advantage and reasoning for the selection of this advanced hybrid technology to cope with the power system challenges of future mining projects. It also delves into the potential problems and how to address them.

By Peter Kolitsch, Galyn Rippentrop

INTRODUCTION On April 14, 1994, the joint venture of Kiewit Construction Company and Kenny Construction Company was awarded a 76 million dollar contract for the construction of the New Hampshire Avenue Tunnels in Washington D.C. The Notice to Proceed was given on May16, 1994 and scheduled completion is September 1997. This project is one of five contracts for the Mid-City E Line as part of the Washington Metropolitan Area Transit Authority (WMATA)Greenbelt Route. Once completed, the Mid-City E Line subway tunnels will connect service between the U Street-Cardozo and Fort Totten stations (See Figure 1). The New Hampshire Avenue Tunnels project consists of approximately 6800 feet of twin single track subway tunnels, three vertical shafts, associated utility work and comprehensive restoration work. Section E4b involved two methods of tunneling along the project alignment. The first method consisted of the well known soft ground open face shield driven tunnel and the second method consisted of tunnels driven using the New Austrian Tunneling Method (NATM) . The NATM section of twin tunnels begins at the Buchanan Vent Shaft and proceeds approximately 2630 feet under Rock Creek Cemetery, including the Farragut Emergency Access Shaft and connects approximately 390 feet beyond to the existing Fort Totten running tunnels (See Figure 2). Special considerations had to be given to the portion of the tunnel alignment which passed beneath Rock Creek Cemetery. The analyses and subsequent selection of the tunnel support system were based on anticipated geological conditions and the sensitive tunnel alignment. The New Hampshire Avenue Tunnels project was the second soft ground NATM project in Washington D.C. The first, by no coincidence, was completed at the adjacent Fort Totten Station and Running Tunnels Project by Mergentime/Hochtief, AJV. Currently, on a nearby WMATA jobsite, the J.F. Shea Construction Company has started a third NATM soft ground tunnel. Tunnel support systems were studied with respect to three tunneling methods: •A one-pass system consisting of a bolted precast concrete segmental lining •A two-pass system consisting of an unbolted precast concrete segmen

Jan 1, 1997

I reached New York at the start of my second South American adventure on Jan. 9, 1916. In the Anaconda office I found that we were not to take the steamer for two weeks which gave me time to study reports on Potrerillos and Corocoro. Reno Sales, whom I had met in Butte only casually, was to go with us to South America. Though he was only a little older than I, he was already an unquestioned leader of our profession, and we became and remained good friends. William Braden was in New York and would return to Santiago with us. Tom Hamilton would also be returning from a vacation. Leighton Stewart, a young engineer who was to work for Braden, was going on the steamer with us, taking along his wife. And of course Dr. Ricketts would go along. He had just become engaged to John Greenway's half sister, Kate Greenway, and in order not to be away from her longer than was necessary, he did not reach New York until a day before we sailed. This made eight of us who would be in the party. We were to go to Corocoro first, as Braden had taken an option on the Chilean company there. Development was already under way. As reports came in by mail we tried to get as good an idea of the property as we could before the actual examination. Mr. Thayer "put us up" at India House, one of the best lunch clubs in New York, and Reno and I ate our lunches there almost every day. Thayer, Braden, and Cornelius Kelley, who was to succeed Mr. Ryan as president of Anaconda, joined us when they could. At the lunches they told us about the under- ground war in Butte a few years earlier. When I wrote my chapter on the Butte wars in Romantic Copper more than 15 years later I could not help being biased a bit by my friends, all of whom were on the Anaconda side. But their opponents in the Clark and Heinze camp were just as biased in their comments on my book.

Jan 1, 1976

By Margaret Armstrong, Chris Roth

One advantage of kriging is that it provides both an estimate of the block or point grade, and an indication of the local precision via the kriging variance. If one assumes that the estimation errors are normally distributed, then confidence intervals for the grades can be calculated. But in mining, grades are rarely normally distributed; in general, they are skew. This is particularly true for precious metals. In this paper we study confidence intervals for variables with non-normal distributions. Using a non linear geostatistical technique, the grades are transformed into their normally distributed equivalents. Confidence intervals are obtained for these normal variables, and back transformed to give the corresponding confidence intervals for the grades, for either points or blocks. This approach is applied to gold data from the Witwatersrand basin in South Africa.

Jan 1, 1996

By Siddhartha Agarwal

The mining industry collects a significant amount of operational data. However, gleaning useful information from the terabytes of data is difficult, and not just because of the sheer volume of the data. Therefore, an automated tool was developed at the University of Alaska Fairbanks to go through data and apply sophisticated statistical and neural network techniques in order to identify the data streams that are important to a process. This paper presents results from the tool as applied to SAG mill data from a gold mine. The results were compared to results achieved earlier with available commercial modeling tools. The comparison indicates that there was little or no loss in performance by automating the very complicated process of neural network modeling. Therefore, the intent of the exercise, to examine if complicated modeling tasks can be automated, was realized. Mining Engineering, 2011, Vol. 63, No. 12, pp. 52-54. Official publication of the Society for mining, metallurgy and exploration, Inc.

Jan 1, 2011

By L. C. E. FEIO, R. RAMSDEN

In many parts of the world deep level mining relies heavily on the use of refrigeration for providing safe thermal underground conditions. The trend in South Africa in recent years has been to locate the refrigeration plants on surface and to use these plants to chill water that is then distributed throughout the mine. The surface cooling installation normally consists of a pre-cooling tower in which water is first chilled before it is sent to one or more refrigeration plants for further cooling. Presently, the majority of these refrigeration plants use CFC refrigerants; however, to conform with the Montreal Protocol, these plants will have to be replaced or converted for use with alternative refrigerants. The optimum design criteria for installations using the new generation of refrigerants will be affected by their characteristics and are likely to be different from those currently in use. In light of these developments the industry is examining a number of alternative systems for future installations including water vapour refrigeration. Factors that affect the decision on the type of refrigeration system to be used in mine installations are reviewed. INTRODUCTION Gold mining has been carried out in South Africa for over 100 years and most of the reserves close to surface have been mined out; this has led to mining taking place at greater depths, approaching 4000 m below surface. One of the consequences of operating at these greater depths is that it is necessary to install refrigeration plants to cool the ventilation air so as to provide safe and healthy working conditions. With the current low precious metal prices there is pressure on mines to cut costs and in recent years there has been considerable effort devoted to the design of more cost effective and efficient refrigeration plants and cooling systems. In the last 10 years there have been many studies into the use of ice for specific applications (Eschenburg et al., 1986; Hemp, 1988 and Ramsden and Lloyd, 1992) and at present there are three ice making plants in operation on South African mines, each of which produces ice in different processes. In addition, detailed design studies have been carried out on the "split ammonia system" (Napier and Patterson, 1992). In this refrigeration system the evaporator is located underground close to where the cooling is needed, whilst the condenser and heat rejection system is on surface. As far as refrigeration plants are concerned the trend has been to move away from standard package units to custom built refrigeration installations. This has given the design engineer greater flexibility in the choice of key components for refrigeration installations. For example both screw and centrifugal compressors are used, the heat exchangers for the evaporators and condensers may be either plate or shell and tube, and in a number of installations evaporative condensers are used. In addition, the following refrigerants are in use, R12, R22 and ammonia. The acceptance of the Montreal Protocol and its amendments by the South African government will restrict the use of CFC refrigerants and it will be necessary to re-evaluate various refrigeration systems, including those that do not use conventional refrigerants, such as air cycle and water vapour systems, for new surface installations. Although new systems and refrigerants are being developed, only the following refrigeration installations will be compared in this paper: - a refrigeration system using R134a which has properties similar to R12 - refrigeration system using R22 or a new alternative refrigerant with very similar properties - an ammonia refrigeration system - a water vapour refrigeration system The benefits of new cooling systems are not discussed in detail, since they are largely mine specific and outside the scope of the present paper. Since the optimum design for an air cycle system (del Castillo, 1988) is dependent on the mine layout, this system is also not included.

Jan 1, 1993

By Michael F. Tucker

Dealing successfully with intercultural issues is critical for success on an international assignment. This is true not only for employees but for the accompanying spouses and children as well. This paper presents a set of research-based competencies required for successful life and work in another country, such as open-mindedness, flexibility, and respect for the beliefs of others. Best practices for training employees and their families bound for international assignments are also presented.

Jan 1, 2001