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By N. Ward

The Gualcamayo Mine is located in the Andes Mountains north of San Juan, Argentina (Figure 1). A property of Yamana Gold Inc, it declared commercial production in July 2009 and has a total mineral reserve and resource base of approximately 88,000 kg of gold. Crushing operations for the open-pit mine are located in a 13,500 m3 underground cavern with a ceiling height of 22 m. More than 3,600 m of tunnels are used to access the cavern and convey the ore. The Project as described in this paper relates to the design and construction of the Main Cavern, Conveyor System Exit Tunnel, the Mechanical System Access Tunnels, and two 4.20 m diameter shafts (Ore Pass #1 and Ore Pass #2) as shown in Figure 2. [ ] Preliminary engineering for the Project was performed by Hatch Chile. Rizzo Associates Argentina, S.A., a division of Paul C. Rizzo Associates, Inc (Rizzo) was contracted to provide geomechanical and geotechnical support for the construction of the access tunnel system and geomechanical design and construction supervision for the cavern and shafts.

Jan 1, 2011

By Greg Beckstrom

On Oct. 1-3, SME?s Twin Cities chapter (SME TC), in cooperation with the University of Minnesota ? Duluth?s Precambrian Research Center (UMD-PRC), cohosted a symposium on silica sand mining and processing. The conference was held at the Earle Brown Heritage Center near Minneapolis. The symposium was followed by a day-long field trip to operating mines, processing plants and loading facilities located in southwestern Wisconsin. Speakers and attendees at the symposium included university professors, industry experts, regulators, mining company representatives, equipment suppliers, consulting engineers and service companies. Approximately 320 people attended the conference. In addition, about 50 people who oppose mine development and the oil and gas industry showed up to voice their displeasure with the event and those companies that operate in this space.

Jan 1, 2012

By Myles E. Robinson

During the last decade there were pronounced changes in the competitive pattern of the fossill fuels It is proposed to trace these trends and describe inter-fuel competition, first as it relates to the economy as a whole and then more specifically to examine competition of the fossil fuels as these share the electric utility market. Table 1, Competitive Fuels and Water Power Used in the United States, 1950-1959, shows the growth in the consumption of coal, oil, gas and water power 'during the past decade. Uses which are not directly competitive among the fuels, such as tractor fuel, carbon black, and consumption of petroleum products in the making of synthetic rubber, have been excluded from these statistics. The experience of the three fossil fuels in competition since 1950 shows natural gas expanding more rapidly, than oil by roughly twice as much, 219.0 percent' compared to 124.1 percent growth in B.t.u.s of oil consumed in the ten-year period. Percentagewise, water power little more than held its own, and coal, including anthracite, actually decreased more than one-fifth.

Jan 1, 1961

By David D. Eyer

In today's world coal market, coal quality is becoming increasingly important. Often the coal quality parameters are one of the crucial considerations in the development of a coal mine. Because of the user's tighter specifications and because of strict environmental regulations, coal producers are being called on to predict with increasing accuracy, not only the quality of their product but also the variability of that quality. This area of reserve evaluation is naturally receiving a great deal of scrutiny. Consolidation Coal Company has developed reliable and sophisticated methods for predicting coal quality, but the company's efforts continue to search for even better techniques. The following is a step-wise summary of The methods currently used by consolidation coal company, with A recent project used as an example. Two of the newer, and as yet experimental techniques will be briefly discussed.

Jan 1, 1980

By Brad Grothen, Lok Home

The choice of TBM type is never easy, but it becomes especially challenging when faced with a hard rock tunnel with expected high water flows and pressure. Slurry Shield tunneling has a long history of being used in these conditions to minimize the risk, though this method has brought with it other risks along with cost considerations. At recent projects around the world, another method has been proven to effectively manage these project risks without utilizing Slurry Shield tunneling: Shielded, NonContinuous Pressurized (NCP)-TBM tunneling in rock with a comprehensive grouting program. In this paper, the authors will analyze the use of Shielded NCP TBMs at projects around the world as compared with slurry shield tunneling in rock under water pressure. Recommendations will be given in order to establish a clear picture of the optimal tunneling method.

Jun 13, 2021

By M. Fan

Dry coal separation technology has particular advantages in the applications in arid and cold regions, or low rank coal separation. The hazardous pollutants in low rank coals can not be efficiently removed by conventional wet coal separation processes because a considerable amount of porose and easily friable low rank coals suffer serious particle size degradation problems in water. In this paper, a novel dry coal separation method with a vibrated air-fluidized bed of magnetic fly ash and magnetite is put forward for dry coal beneficiation. The magnetic fly ash used in this study was derived from fly ash obtained as a byproduct of coal combustion. The vibration?s effect on the uniformity and stability of a magnetic fly ash air-fluidized bed was studied. The 6×0.5 mm dry coal separation results with a vibrated air-fluidized bed of magnetic fly ash and magnetite showed that the probable error E value of separation is 0.06-0.08 t/m3.

Jan 1, 2009

By E. A. Rychkun

Mining and environmental objectives have traditionally been in conflict. This conflict reflects a delicate balance between the need to spend money to protect the environment, and the need to save money by extracting minerals efficiently. In an increasing number of cases, profit margins diminish rapidly with new environmental regulations and reactionary measures. Forced cleanups and increasing restrictions are unwelcome expensive processes. A practical solution lies in planning rather than reacting. This requires the ability to precisely quantify and qualify environmentally sensitive problems by providing effective engineering tools to model, visualize and analyze subsurface conditions. Prevention of environmental conflicts, and effective cost control are both rooted in the mining company's ability to construct accurate models, monitor changes, assess contamination risks and to design effective remediation plan. This paper presents a case study where these issues are addresses through the application of a new and innovative technology.

Jan 1, 1993

By Pawan Bharadwaj, Wim Mulder, Thomas Tscharner, Guy Drijkoningen, Rob Jenneskens

"The Earth’s properties, composition and structure ahead of a tunnel boring machine (TBM) should be mapped for hazard assessment during excavation. We study the use of seismic-exploration techniques for this purpose. We focus on a seismic system for soft soils, where shear waves are better and easier to interpret than compressional waves, as has been shown over the last decade. The system is intended to be deployed on the machine’s cutter head, with a few seismic sources and sufficiently many seismic sensors to tackle spatial variability and noise characteristics. An important property of the newly developed system is its ability to process data with very little human interaction. Images need to be available in near real time, without human interactions slowing down the imaging process. This can be achieved by employing Full Waveform Inversion, which minimizes the difference between modeled and observed data. Because this method may suffer from local minima in the cost function if the data lack low-frequency information, we employ a dedicated seismic source that can generate sufficiently low frequencies for the relevant length scales. With data acquired in a number of field settings that mimic realistic TBM configurations, we show that the designed seismic system can successfully look ahead of the TBM and offers a valuable capability to support decision-making during tunnel excavation. INTRODUCTION While excavating a tunnel with a Tunnel Boring Machine (TBM), the geology and the ground conditions along the planned tunnel trajectory need to be investigated in order to safely and efficiently carry out the underground operations. This entails detecting the occurrence of boulders, foundations, pipes and faults, necessary to prevent hazards and time-consuming delays in the tunnel boring operations. In order to facilitate ground prediction ahead of a TBM, techniques as used in seismic exploration can be deployed. Two components common to seismic-exploration techniques are data acquisition and processing, the latter including inversion. We will discuss each of these for the application to tunnel excavation with TBM, in particular for soft soils."

Jan 1, 2016

By S. Simske, K. Boakye, D. Winters

The application of digitization to operations and logistics is commonplace. From advanced data analytics to intelligent networks, digitization offers tremendous opportunities to create value, raise the efficiency of production processes, and reduce emissions. Several manufacturing industries have already implemented solutions to good effect by using digitization. Mining companies, for example, are using historical data about equipment health to predict potential failures, while aeronautics and automotive companies are using robotics and end-to-end digital twins to improve their design and production processes. Not surprisingly, first adopters of digitization in many industries have gained an edge over their competition. The cement and aggregate industry can better manage the enormous energy consumption, rising cost challenges, inefficient uses of raw material, logistic problems, emissions, and overall process complexity that are inherent in their operations by doing the same. This paper presents the results of a literature review and analysis and conveys the challenges for adaptation and implementation of digitization and artificial intelligence (AI) in the cement and aggregate production industry.

Mar 2, 2022

By ETHAN FUSTER, STEPHEN LEE, Richard Ray

By offering savings in space and capital cost compared to ducted axial and centrifugal fan systems, horizontally mounted jet fans are commonly used worldwide to ventilate vehicular tunnels. They discharge high-velocity jets to transfer momentum to the surrounding airstream to induce longitudinal flow in the same direction as the jet. Vertically mounted jet fans installed in exhaust shafts have been successfully used to ventilate a large passenger rail overbuild in New York City. A comparison of shaft dimensions, vertical placement of the jet fans and measured shaft airflows is presented to evaluate optimum jet fan configurations. Measured shaft airflows are compared to airflows predicted by computational fluid dynamics (CFD) simulations of a three-dimensional model of the overbuild.

Sep 1, 2022

By G. Luttrell, S. Keles, M. Eraydin, R. Yoon

The dewatering of fine particles is energy intensive and often requires costly capital expenditures. To address these issues, a series of advanced dewatering technologies have been developed at Virginia Tech. These include novel dewatering aids that enhance the performance of existing filtration equipment and an innovative hyperbaric centrifuge that utilizes both air pressure and centrifugal force for dewatering. The moistures obtained using these processes are 30-50% lower than those obtained using conventional methods. Another dewatering technology, known as the hydrophobic displacement process, can reduce product moistures to a level previously attainable only through the use of thermal dryers. This article presents test results obtained with these various advanced dewatering technologies along with estimates of the power consumption for each process.

Jan 1, 2007

By Thornton L. Neathery

The low-grade talc deposits in Tallapoosa County, Alabama, are associated with a mafic-ultramafic rock complex that is part of a widely distributed schist and gneiss group. These rocks form a synform structure overlying Inner Piedmont lithology. Paragenetic sequence of the Tallapoosa talc is interpreted as enstatite-anthophyllitetalc. Talc occurs as massive boulders formed by the alteration of enstatite-anthophyllite and as finely disseminated discrete particles in the enclosing saprolite matrix. Weathered rock reaches depths as great as 60 feet. The quality and quantity of the talc, however, are variable. Mineral analyses of the talc-bearing samples, by petrographic grain count, indicate a talc content of 16 to 26 percent. Most of the talc occurs as plates or scales that are moderately stained with limonite. Fibrous talc also occurs in the deposits and is often mistaken for anthophyllite asbestos which is intimately associated with the talc. The size, shape, and occurrence of the talc deposits precludes any method of min¬ing other than open-cut. A small-scale mining operation began in the district in 1969. Potential capacity of the operation is 5, 000 tons per year. Inferred reserves, based on field investigations, are placed at approximately 8 million tons. Approved for publication by the State Geologist, Geological Survey of Alabama.

Jan 1, 1970

By Masaji Kato, Yuusaku Tominaga

To maintain good condition of ventilation for both safety and economy, many regulators are installed in a network. In case the open state of a regulator is different from the set point, identification of a broken regulator and a countermeasure to recover airflow distribution in a network must be initiated as soon as possible. An experienced mining engineer can sense a deviation from ordinary airflow quantity. In this paper, a new system to monitor all the regulators in a network is introduced. The basic concept of the system is utilization of both human sensing of airflow rate and computer simulation to understand the macroscopic characteristics of a ventilation network. A fuzzy pattern distinction method is used to process human determination of airflow rate that may be ambiguous. The applicability of the system is demonstrated using the ventilation network of the Horonai coal mine, Japan. In particular, it is shown that the system can identify the regulator to be repaired from information supplied by workers relating to air- flow in a few sensor branches.

Jan 1, 1997

By J. D. Patsey, G. T. Lineberry

Introduction A computer program was developed for analyzing drum-type hoists before modifying an existing system or designing a new one. Its use permits the preliminary evaluation of a system before seeking technical assistance from mine hoist designers and manufacturers. The user-friendly program accepts a variety of data and analyzes hoisting systems for any balance state. The program can be used to calculate skip capacity to yield a desired production rate, solve for drum face width, select a permissible wire rope, estimate total horsepower of the hoist plant, and estimate annual power cost. Whether required for a large mining complex or for a relatively small operation, a hoisting system must be carefully designed to ensure the efficient, reliable, and safe flow of material. Because shaft sinking and hoist installation can total between 2.5% and 3% of the cost of opening a deep mine, proper hoist selection is critical. Today's mining engineer has at his disposal the most powerful design and analytical aid ever, the microcomputer. There is, unfortunately, limited software for the study of hoisting systems, unlike that for other materials handling equipment (Manula and Albert, 1980; Prelaz et al., 1964; Bucklen, 1969; Thompson, 1985). HOIST reduces a time-consuming set of calculations to a concise package of interrelated subprograms. A literature review revealed no common-user programs to analyze hoisting systems, although at least four major hoist designers/manufacturers/installers have their own in-house programs. To provide a tool with which the mining engineer could preliminarily analyze a materials hoisting system or could check the calculations of a hoist contractor, a computer program was developed. HOIST was written in BASIC for the IBM-PC for ease of program adaptation and to encourage field use on compatible systems. Details of program development are omitted, since the basic principles of hoisting analyses are relatively straightforward, simple, and readily accepted (Harmon, 1973; Nordberg, n.d.; Adler, 1957). Program features, intended usage, and benefits of the computerized solution are emphasized over theory development and mathematical rigor. Background The mine hoist system that is selected and installed at a mine is the "lifeline" of that mine, with installations lasting 20 years or more. Thorough study is warranted to ensure that productivity demands are met at a minimum cost per ton. The increased cost of a large, powerful, high-speed hoist must be offset by increased production to justify its selection. To optimize this tradeoff, an extensive hoisting analysis should be performed. The analyses to properly size the skip (or cage), the drum, and the hoist drive are conducive to computerization, permitting rapid evaluation of changeable operating and design parameters, such as velocity, acceleration, state of balance, and productivity demand. The program is particularly useful in conducting sensitivity trials, such as investigation into the effect of change of productivity on skip capacity and on horsepower of the hoist drive. HOIST is currently limited to the study of drum-type hoists with cylindrical drum(s). However, only minor changes to the program would permit analysis of friction hoists and conical drum configurations. Model development and testing The program is based on accepted equations and physical relationships. Examples of manual calculations formed the basis for decision points and program branching. Data is input in the order that it would be needed if the problems were solved manually. The choices are arranged likewise. HOIST was developed in sections, with manual solutions performed to check program logic. The testing became more rigorous as sections were completed. Output from one section becomes input for following sections, as appropriate. The simplified flow diagram of HOIST is given in Fig. 1.

Jan 2, 1987

By William Hodder, Ehsan Alavi, Muhib Hussain

Disc Cutter Wear is influenced by several geological and technical factors and excessive wear can have a major impact on the excavation efficiency of Tunnel Boring Machines (TBM). Disc cutter replacement events cause a disruption to the construction schedule and costs, and should be minimized throughout the project to the extent possible. A well-executed cutterhead inspection and maintenance plan can help mitigate abrupt cutterhead interventions and reduce its effect on project schedule and cost. This paper examines cutterhead inspection and disc cutter replacement events as well as subsequent wear data recorded in the first 7km of the 10.3 km long, 6.3 m diameter Coxwell Sanitary Bypass Tunnel (CBT) project in Toronto, Ontario. The CBT alignment is mainly through Georgian Bay Formation shale.

Dec 1, 2022

By R. S. Datta

Regulations on sulfur emissions have caused the electric utilities to evaluate various methods of meeting them. Low-sulfur, low-volatile coals can be burned alone or blended with high-volatile? coals. This option may be a cost-effective alternative to the installation of scrubbers on coal-fired combustion systems. In some blending applications, problems may be encountered because the low sulfur content and high calorific value of the low-volatile or other clean coal allow it to economically upgrade extremely poor quality coal. While this is done to meet specification purposes, actual boiler performance may be dominated by the poorer quality coal. Thus, the reputation of the low-volatile or other clean coal suffers. As a result of laboratory and full scale testing, conducted over the last five years, a model has been developed to evaluate the relative combustion characteristics of various coals and coal blends. A database for different coals has been gathered. This paper presents the model and shows how power plants and coal mine personnel can use it to evaluate their coals from different sources. It can be used to blend two or more coals from different sources so that thee blended coal has flame stability characteristics which are similar to those of the baseline coal.

Jan 1, 1991

By Y. C. Guan

The cementation of gold on to copper and zinc in ammoniacal solutions has been studied using rotating disc electrodes. The cathodic reduction of aurous ammine was studied on a gold rotating disc electrode and the anodic dissolution of copper and zinc was studied in the absence of aurous ammine. The cementation rate was found to be a first order with respect to the concentration of aurous ammine and to be proportional to the square root of the disc rotating speed. Based on the results obtained, it was concluded that the cementation reaction was controlled by mass transfer of aurous ammine to the reaction surface under the experimental conditions.

Jan 1, 1995

By B. T. Field

Pyroprocessing systems range from low temperature dryers to high temperature reactors. The materials and process requirements cover a broad spectrum. It is not the intent of this paper to do a detailed examination of individual processes and equipment, since that can be found in a multitude of other sources; rather it is the intent of this paper to examine the key process variables and offer empirical guidelines to assist in a user?s overall evaluation.

Jan 1, 1998

By J. Kenneth Wittle

The DC Graphite Melter has been shown to be capable of processing radioactive waste materials. The process is characterized by its high temperature capability and operation in a closed system. From an environmental perspective, the control of emissions coupled with destruction for hazardous organic materials is mandatory. These same characteristics may be applicable to the minerals processing industry. Under normal operation, the system reaches temperatures for nominal operation of 1600°C, with an arc temperature in the order of 5000°C. The system temperature is determined by the melt temperature of the material being processed. In testing of a 750 lb/hour unit, temperatures of 2200°C were reached. Current focus is on finding waste treatment and metals recovery opportunities in the metals processing industry for his innovative technology.

Jan 1, 1999

By E. L. Smith

The development of larger size flotation machines, which started in the 1950's and 1960's, is still proceeding. The largest mechanical flotation machines avail-able today have unit volumes in the range of 38.2 to 43.9 M3 (1,350 to 1,550 cft). Designs for mechanical flotation cells of unit volumes as large as 70.8 m3 (2500 cft) are available. The development of these "giant" flotation machines has been and continues to be motivated by the increasingly critical forces of higher energy and capital costs, decreasing ore grades, and lower (real) prices for the products. As an expansion of a previous publication, this paper reports the further development of an improved mechanism for these large flotation machines. The starting point in the develop¬ment of a new mechanism was the identification of design and performance features of existing machines where improvements were desirable. The result of this work was a mechanism which s is an improvement over existing designs. This new design is characterized by an efficient overhung stator and a vortex profile rotor. The overhung design of the stator removes unnecessary and undesirable baffling in the lowest parts of the tank, while maintaining a quiescent froth layer. This results in lower power consumption and better pulp circulation and solids suspension. The vortex profile rotor acts as an efficient pump, with higher pulp recirculation rates as evidenced by the increased air dispersion capabilities, good solids suspension, and low power consumption.

Jan 1, 1983