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By D. Veigel, J. D. McKay

Model enhanced Expert control has been implemented at the Newmont Lone Tree mill grinding plant as well as rule based Expert control for flotation and thickening circuits. The project has been successful in producing benefits but more importantly has contributed to an ongoing effort for continuous process improvement. This paper discusses how the control at Lone Tree has evolved and the part that Expert control has played in the overall improvements made. Specific examples of how the advanced control has integrated with instrumentation and stabilizing control are given and illustrations of how it has been effective in defining limitations and bottlenecks in the process or process control areas are provided.

Jan 1, 2002

By G. F. Revey

Most commercial explosives contain from 70% to 94% (by weight) ammonium nitrate. When some of the explosives end up in shot rock and ore, through either spillage or incomplete detonation, ammonia and nitrates can leach into the ground water. In recent years, state and federal regulators have applied more stringent water-quality standards, particularly at new mines and development projects. When mining conditions permit, bulk ANFO, a mixture of ammonium nitrate and fuel oil, is the explosive of choice. ANFO is less costly than other explosives but it dissolves readily in water. Several case histories in the United States and Canada show a clear connection between uncontrolled losses of bulk explosives and high nitrate levels in mine effluents. Mining companies have tried several approaches to reduce ammonia and nitrate levels in groundwater. These approaches range from controlling explosive losses to treating the mine effluents. In this paper, controlling explosive losses is addressed For both packaged and bulk explosives, guidelines to limit losses during storage, handling and use are described in detail.

Jan 1, 1997

By Jean-Claude Bianchini, Paul Bauernfeind, Erwin Gartung

Introduction The city of Nuremberg, located in Bavaria in the Federal Republic of Germany, started building a subway in 1967. The construction operations began in a southern suburb, where no complications were encountered in the design and execution of the job. As the first subway line approached the downtown area of the city, the civil engineering challenges increased rapidly. Tunnels had to be excavated next to, or below precious historical buildings, and the work of the responsible engineers was closely watched by the public, who were very anxious about any damage to the existing beautiful old houses and churches. The job has been handled successfully to date in cooperation with the owner-designer, the geotechnical consultant and the contractors, who jointly went through a process of systematic learning and gathering of experience, and who developed a modern tunneling technique specifically tailored to the natural properties of the encountered ground conditions and the requirements of the city of Nuremberg. The application of scientific methods has been an important part of this development. Research into the geotechnical properties of the predominantly encountered soft Keuper sandstone, studies of the geomechanical performance of grout reinforced sand sections and finite element analyses of various tunnel problems for the prediction of displacements, for the assessment of stability, or

Jan 1, 1979

The ever-increasing power (and decreasing cost) of computers has opened up substantial oppor¬tunities for 'Vision'-based systems in both on-line and off-line control. This paper reviews image analysis applications in use at the Julius Kruttschnitt Mineral Research Centre (JKMRC) for: •blast and mill feed size monitoring; •AG/SAG mill model-based control; •mineral liberation; and •froth flotation control. The SPLIT™ image analysis system is being used to estimate muck pile and ROM feed sizings. AG/SAG mill feed sizing is being used in a dynamic model for mill control. A new generation mineral liberation analyzer has been developed with Philips Electron Optics. The Philips-JKMRC mineral liberation analyzer offers a substantial improvement in resolution and speed over previous developments. While on-line liberation control continues to be something of a pipe dream, measuring liberation "one shift behind" is now feasible. A robust instrument has been developed to measure flotation froth bubble size and velocity. The instrument also derives a parameter that allows different froth textures to be distinguished. The instrument has been used for on-line control in coal and sulfide flotation. For coal froth, an online ash estimate has been achieved at one site and is being tested at other sites. Overall, image analysis is finding many applications in mineral processing and control.

Jan 1, 2000

Various computer packages are now available for balancing data obtained from complex concentration plants. It is well established that the filtered data generated by these programs are statistically better than the raw data. However the degree of improvement as well as the accuracy of the estimated variables depend strongly on the propagation of measurement errors through the estimation algorithm. Therefore, for the subsequent use of the filtered data, their confidence intervals are as important as the data themselves. Variance of filtered variables have been derived in a very general way for any arbitrary flowsheet and when data originate from various sources such as flowrates, chemical assays, particle size distributions and pulp percentages of solids. The theoretical formulae are incorporated in the BILMAT package for mass balance calculation and illustrated on various flowsheets involving grinding, classification and flotation. The validity of the proposed method is discussed by a comparison to a Monte Carlo approach, for a simple processing circuit.

Jan 1, 1986

By Ahmet Unal

Inexpensive and effective means of delivering courses to mining engineers who live at remote and scattered locations remains to be a challenging issue. Computer-based instructorless but interactive multimedia delivery is a good substitute to traditional short courses and one-way broadcasts. Such a system, enhanced with a wide area network, is an inexpensive alternative to two-way broadcasts and even to a traditional university. Course material can either be delivered on compact disks (CDs) or on-line from the host servers over the phone lines using a personal computer and a modem. Although technically not feasible using ordinary telephone service lines at the present time without further modification, advances in this field indicate that this up and coming medium may dominate the competition in the future. This paper investigates the present and the future of this technology and discusses the experiences gained in creating and disseminating a prototype multimedia CD which was created at the Rock Mechanics and Explosives Research Institute of the University of Missouri-Rolla to teach a portion of a course in Ground Control. The hardware and software used in creating the audio, 3-0 graphics, animation dips, video clips, and movies are listed. The structure of the program and the way how interactivity was achieved is explained in detail.

Jan 1, 1996

By Jouko Suominen

The basic development of various mining equipment has been strongly influenced by two objectives; improving economic results and safety aspects. Both of these factors contribute to increased requirements of mechanization and automation in different parts of mining processes. When we are limiting the discussion the crushing circuits, automation has two dimensions, one being the component automation, or intelligence, the other being automation of complete processes. Both of these subjects are closely tied up, the former being a condition for the latter. The key technologies of crushing automation are transducers, programmable logics and computer software. Also equipment technology continually faces new challenges, which result even in totally new product families. One example of this kind of development area the track-mounted, integrated crushing systems, where design criteria have been simple control, unmanned operation, and flexibility in changing requirements. This crushing system, or philosophy, offers excellent possibilities for new concepts in various underground and open pit applications, connected with automatic process control. Following presentation is a summary of aspects, of haw a crusher manufac¬turer sees the development of automa¬tion as an integral part of equipment technology and development.

Jan 1, 1989

By William C. Paschen

Damen Avenue to Roosevelt Road, the Tunnel and Reservoir Plan (TARP), a Deep Tunnel Project for the Metropolitan Sanitary District of Greater Chicago consists of 25,189 lin. ft. of 32 ft. tunnel with 1 ft. 0 in. concrete liner throughout. The 17,100 ft. main tunnel connects at both ends with two other Deep Tunnel contracts. A branch tunnel connecting to the mainstream tunnel, commences approximately 4,140 ft. from the construction shaft and runs 8,089 ft. south and terminates at the Racine Avenue Pumping Station. Shaft work consists of one 28 ft. 6 in. diameter construction shaft, one 3 ft. 6 in. diameter access shaft and 25 drop shafts-four of which have vent shafts. The drop shafts vary in diameter from 4 ft. 0 in. to 17 ft. 0 in. All shafts vary in depth to invert from 225 ft. to 235 ft. Work has been underway for 16 months and as of this writing the construction shaft and access shaft are complete. Seven shafts have been excavated and concreting operations have started in four of them. The starter tunnel is complete, the mining machine has mined 250 lin. ft. and the muck removal system is in full operation. The contractor for the project is a joint venture of Paschen/Morrison-Knudsen/Kenny. Paschen Contractors, Inc., Chicago, Illinois is the sponsor. The total contract amount is $107,837,300.00.

Jan 1, 1979

By Robert Sutton, Milan Sjaus

Conveyor pulleys are an important and integral component of a conveyor. Conveyors work in sequence to make up conveyor systems. Each conveyor system is only as reliable as its crudest component. If the pulley fails, then the whole material handling system stops. So what is the effect of this downtime? What are the costs of repair? How much are we willing to pay to solve the problem? What should we spend to prevent an unscheduled shutdown? Do we use the technological improvements at our disposal or do we ignore them to satisfy immediate cost savings? This study will focus on the cost of pulleys relative to the total conveyor cost, the cost of downtime, the maintenance costs and the costs for resolution of the problem. Some philosophic and design concepts are injected for illustration and discussion.

Jan 1, 2000

By M. Kumral

The in-situ mineral characteristics of a deposit are simulated by sequential co-simulation and averaging the simulated characteristics within specified block volumes creates a three-dimensional block model. This model is then submitted to optimal open pit and production scheduling algorithms. As the market values of industrial minerals depend on the satisfaction of predetermined blending criteria rather than metal content, a Linear Programming (LP) scheme has been used to identify all blocks that can be included in the blend without violating the grade requirements. The Lerchs-Grosmann algorithm using the blocks identified by the LP program determines optimal pit limits. All blocks that lie outside the optimal pit are removed from the system and the blocks within the optimal pit are submitted to the production-scheduling algorithm. Production scheduling optimisation is done in two stages: Lagrangean parameterisation, resulting in an initial sub-optimal solution, and multi-objective simulated annealing (MOSA) improving the sub-optimal schedule further.

Jan 1, 2002

By A. W. Khair, M. Ahmad

Bit wear has been proven to have a significant effect on respirable dust generation in coal cutting system. The mechanism of bit wear can be adhesion, abrasion, oxidation, or diffusion, depending on cutting conditions. This paper presents a portion of an extensive ongoing series of studies to better understand the principles of bit wear and dust generation. Used bits collected from underground coal mines were analyzed to identify the basic principle of bit wear in coal and rock cutting. Distribution of weight loss and conical height loss of worn bits were studied and bit wear was divided into four stages according to weight loss. Utilizing these worn bits, Laboratory experiments have been camed out to study the effects of bit wear on coal cutting system and respirable dust generation. An Automated Rotary Coal Cutting Simulator was use to perform the experiments. Acoustic emission monitoring is applied to study the effect of bit wear on fracture formation and dust generation.

Jan 1, 1992

By J. Pang, S. Chander

The mechanisms of chalcopyrite oxidation in alkaline solutions have been studied using cyclic voltammetry and impedance spectroscopy techniques. The cyclic voltammetry was used to elucidate oxidation/reduction reactions, whereas impedance spectroscopy was used for in-situ characterization of the interface. To analyze the impedance spectra, equivalent circuit models were constructed based on a layer- wise growth of reaction products. Parameters of the equivalent circuit were calculated by comparing the experimental spectrum with that expected on the basis of equivalent circuit. From the value of equivalent circuit parameters, properties of the surface layers were inferred. These properties change substantially with the change in oxygen and/or collector concentration in solution. From such changes the effect of oxygen and collector concentration on the contact angle and flotation behavior of chalcopyrite were interpreted.

Jan 1, 1991

By N. S. P. Kumar

INTRODUCTION Development work at Carr Fork Mine of Anaconda Copper Company in Tooele, Utah commenced in August 1974. A decision to install an underground gyratory crusher for primary crushing run-of-mine ore and waste was made in 1976. Higher throughput rates, larger reduction ratios and greater flexibility in terms of meeting immediate and expanded production needs were the main reasons for selecting the gyratory crusher over the jaw crusher. UNDERGROUND MATERIALS HANDLING Underground crushing and conveying system was designed for a capacity of 16,300 mtpd of ore and waste on a 2-shift, 5-day week basis. Engineering and design of crusher complex was performed by Anaconda engineers at Carr Fork. Figure 1 represents the longitudinal section of mine showing the general materials handling system. Mine area is trackless except for materials and production haulage which is run on rail track on both 1200 and 970 levels. Ore from stopes and waste rock from development headings are handled by 3.8 cu m (5 cu yd) Jarco scoops and dumped into 2.4 m (8 ft) diameter ore and waste passes at the 1200 level. The material gravitates down to the 970 level where it is loaded into 12 cu m (420 cu ft) ASEA mine cars using side loading chutes. The muck train, consisting of 15 to 18 cars and two 27 mt General Electric trolley locomotives, is hauled over a distance of 2,300 m (7,550 ft) to

Jan 1, 1981

By I. Edgar Odom

Hectorite is a rare magnesium-lithium clay mineral that occurs at many places in the McDermitt caldera of Nevada-Oregon. Commercial development of several high purity deposits began in 1986. The hectorite that was precipitated in a lake environment formed after the collapse of the McDermitt caldera. Hectorite beds and lenses are associated with volcanic sediments, limestones, dolomites, zeolites and locally sandy bentonites. The high purity deposits appear to be associated with hydrothermal areas. The hectorite consists of extremely small, flake-shaped crystals. Calcium (Ca) is the predominant exchangeable ion. Its color ranges from white to light green. Commercial uses include high-brightness, magnesium-aluminum-silicate (MAS) products, organophilic clays, pulp retention and ceramics. The MAS is used as a suspending agent, binder, stabilizer and thixotrope in aqueous solutions for cosmetics, household cleaners, pharmaceuticals and miscellaneous industrial applications. Hectorite-based organophilic clays are used in printing inks and paints. The McDermitt caldera complex is located astride the Nevada-Oregon boundary west of the town of McDermitt, NV (Fig. 1). The structural complex is elliptical in shape, extending about 43 km (27 miles) north-south and 34 km (21 miles) east-west. This area was the site of extensive volcanism during the Miocene (24 to 18 million years). The complex consists of five overlapping calderas with the oldest at the south end of the complex (Rytuba et al., 1979). Each of the vent areas collapsed and is marked by a ring fracture zone. The ring fractures around the outer boundary of the caldera complex are shown in [Fig.1].

Jan 1, 1992

By William Petruk

Volcanogenic base metal ores contain about 0.5 to 7 g/T Au, commonly as an intermetallic compound with Ag and/or Hg, and to a small extent • "invisible gold" in pyrite and arsenopyrite. The Au-bearing phase (electrum, Au-Ag-Hg alloy, etc.) generally occurs as fracture fillings in pyrite, arsenopyrite and chalcopyrite, and rarely • minute inclusions in pyrite and arsenopyrite. The Au-bearing phase in fractures generally occurs • small grains, and is frequently associated with galena, tetrahedrite and other late minerals. The gold is readily liberated from fractures and recovered by flotation in Ca concentrates. Copper concentrates usually recover around 60% of the gold when the ore grade is around 3 g/t. Higher recoveries are obtained for higher ore grades, and lower recoveries for lower grade ores. Lead and zinc circuits act as scavengers for gold, and recover all the exposed gold attached to small particles. Only unliberated gold, "invisible gold" and very minute gold grains attached to large particles are lost to tailings.

Jan 1, 1990

By Prakash M. . P. E. Donde

1. INTRODUCTION The Washington Metropolitan Area Transit Authority (WMATA) has often taken a leading role in introducing innovative construction technologies to build its transit system. Most recently, Contract Section E-5a, which included Fort Totten Station and Tunnels was constructed utilizing the New Austrian Tunneling Method (NATM) in soft ground. Along with the station and tunnels, two permanent shafts were also constructed in soft ground employing the NATM technique. This project is located within the District of Columbia on the Greenbelt Route. The subject of this paper is to discuss the unique method of construction of these two shafts, and explore the benefits of applying the NATM technique to the construction of deep shafts. The design of the shafts was performed jointly by Jenny Engineering Corporation of Springfield, New Jersey, and Mayreder Consult of Linz, Austria. The designers also provided construction support services and a resident NATM expert at the site during construction. The construction of the project started in April 1988 by a joint venture of Mergentime Corporation and H. T. Construction, a subsidiary of Hochtief Company from Germany. This $48.7 million construction project has been completed. 2. SUBSURFACE CONDITIONS The two NATM shafts are located primarily in Cretaceous-age deposits that are over 100 million years old. These deposits are intermixed and lenticular in nature

Jan 1, 1993

By Rimas Pakalnis, Lyndon Clark, Tom Brady

A major focus of ground control research presently being conducted by the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) is to incorporate data on weak rock masses into existing design relationships, with an emphasis on updating the span design curve for manned entries and the overbreak curve for longhole entries. Both curves were originally developed at the University of British Columbia, Vancouver, BC. The original database has been augmented by information from mines throughout the United States, Canada, Australia, and Europe. The common factor in all these mines is the presence of a weak back and/or walls. In most cases, the ore zone is the weakest rock unit and must be stabilized so that the mineral-bearing rock can be extracted safety. The current NIOSH research attempts to provide rock mechanics tools to assist a mine operator in making economic decisions that will also ensure a safe working environment. This paper documents the Nevada database with a special emphasis on Nevada underground gold mines.

Jan 1, 2005

By DeVerle P. Harris

The structure of an exploration model reflects a number of design considerations, one of which is the question or issue-to be investigated by the model. Thus, a model designed to evaluate the magnitude of risk and its economic implication to optimal decision making at each decision juncture of a multistage exploration architecture differs considerably from one designed to evaluate, say, the long run average cost of discovery, in which the architecture of exploration is suppressed and risk is simply an element of average cost. The perspective of the model examined in this paper is that exploration is investment in (purchase of) information and that the next stage of an exploration program is undertaken only when the expected value of information to be acquired in that stage exceeds its cost. The degree to which this perspective is honored influences considerably model design. Consider two design objectives:

Jan 1, 1989

By V. Prabhu, D. Mantha, R. Reddy

Secondary copper blast furnace slag was treated with carbon to derive the conditions for maximum recovery of copper with a minimum simultaneous reduction of iron oxide. Experiments were carried out to study the effect of temperature, carbon and CaO additions to the slag on the efficient recovery of copper. A two-stage reduction process was also employed to study the efficiency of copper recovery and the results were compared with those of single-stage reduction. The maximum recovery of copper in alloy phase was obtained with 5 % initial carbon in the slag, 2% CaO addition to the slag and at a reducing temperature of 1573 K. Higher grade of the alloy phase with respect to copper was obtained by employing a two-stage reduction process. The results obtained in this study are comparable to those of the earlier research on the recovery of copper from reverberatory furnace discard slags.

Jan 1, 2004

By Sukumar Bandopadhyay

In recent years planning of surface mines in general and reclamation and post-mining land uses in particular have become very complex. Due to the lack of suitable techniques, land use plans are rarely based upon structured decisions. Data collection may be conducted in a rigorous manner and certain analyses may be performed on the data; the decision to put the land to a specific use, however, is finally based upon the intuitive judgment of one or several individuals. This paper demonstrates how techniques from fuzzy set theory can be used in order to select an optimum post-mining land use plan. The various land use planning alternatives have been characterized according to both qualitative information and quantitative factors and the "fuzzy" aspects of the collected information are incorporated into the analyses. In a practical application, the methodology is used to obtain the most reasonable solution to a post-mining land use planning problem in Interior Alaska.

Jan 1, 1986