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By S. D. Thompson

Conveyor belt haulage has become the preferred mainline transport method in under-ground coal mining, especially for multi-unit mines. Optimum designs for belts (width and speed) and surge bins (placement, capacity, and discharge rate) are necessary for minimizing haulage cost. Two computer simulation models, CMaCS and BELTSIM, available for optimizing these designs are compared. These comparison include: modeling, input data requirements, statistical flexibility, accuracy of simulated loading, and execution time.

Jan 1, 1989

By P. Mousset-Jones, F. Calizaya

Ultrasonic anemometry is a relatively new method of measuring the air velocity in underground excavations and is not widely used. The method has been mainly used for surface applications, such as meteorology and fluid flow measurement. Several instruments were looked at to determine their applicability for continuous underground monitoring systems. The units fall into two main categories: variable distance units and fined distance units. The method relies on the acceleration and deceleration of ultrasonic pulses transmitted through a moving airstream. This study presents some of the results of the testing of variable and fixed distance ultrasonic anemometers in a wind tunnel and a mine drift.

Jan 1, 1995

By Roy H. Werner

The environmental demands on the mining industry coupled with rising production costs have created a need for a low cost sludge removal system. The HYDRA* system meets these demands by offering a unique means of removing settled solids from the bottom of a clarifier or a thickener. This underflow system combines experience and proven concepts to form a low cost sludge removal system. The HYDRA system incorporates a flexible design that can be adapted to any settling area. The components are readily available and cost less than a conventional clarifier or thickener. Existing technology developed by preparation engineers provides for retrieval and recovery of mine preparation plant refuse. However, past retrieval methods have been extremely costly. The HYDRA system, because of its low cost, makes the complete process of retrieval and recovery economically feasible. This allows wasted resources to be converted to a saleable product.

Jan 1, 1975

By John C. Bowling

Many recent mine developments in North America are located in remote northern regions with extreme winter temperatures in the range of -20oF to -60°F. In addition, many locations are subject to very heavy snowfall. This paper discusses some of the key considerations in the planning and design of mine plant buildings, particularly concentrators, located in these regions. SUMMARY & CONCLUSIONS The subject is considered under three main headings: I. Building Out line and Structural Frame 2. Wall and Roof Materials 3. Foundations The plan outline of a mine plant building will naturally be governed by the scope and layout of the process equipment it contains. The selection of roof profile, on the other hand, will generally depend upon a number of factors extraneous to the process e.g. snow conditions. When these factors are considered for concentrators in cold locations, a flat or stepped roof will usually be more economical and suitable than a sloping roof. The materials normally used for the structural framework of concentrators are the same as used for other industrial buildings, namely steel, concrete and wood. Structural steel, however, is the most commonly used material for concentrators in

Jan 1, 1971

By J. N. Eskilsson, W. P. Chen, J. L. Kaplin, V. S. Romero

The Massachusetts Water Resources Authority is currently improving its primary water supply system for the Boston Metropolitan area. The improvements planned by the Authority, which provides water for 46 communities and over 2.5 million people in eastern Massachusetts, include the MetroWest Water Supply Tunnel (MWWST) to provide redundancy in the transmission system, a large capacity water treatment plant and extensive covered storage facilities. The 28.3 km (17.6 miles) long, mostly 4.3 m (14 ft.) I.D. MetroWest Water Supply Tunnel will allow repair of the aging Hultman Aqueduct, which for 56 years has served as the transmission main from the water supply reservoirs to Boston. On completion of the tunnel, the old pipeline aqueduct will be repaired and brought back into service as a parallel, redundant transmission main. This paper describes design considerations and the design process for pressure tunnels in general and the MWWST in particular. It provides an overview of how the design of pressure tunnel and shaft components progresses.

Jan 1, 1997

By V. B. Achanti

Reliability of the compressive strength of a coal seam determined in the laboratory is often subjected to debate. Effects of the coal seam's inherent characteristics, specimen preparation, testing procedure, testing condition, and a number of tests often result in drastic variation of the strength data. This paper deals with the development of a testing procedure for determination of coal seam compressive strength in the laboratory. Coal samples from two different coal seams were tested. First, the inherent characteristics of each coal seam such as coal structure, Hardgrove Orindability Index (HOI), Slake Durability Index, proximate analysis, and mechanical properties namely Young's modulus and Poisson's ratio were determined to categorize them in terms of their characteristic severity liable to produce variable strength data in typical laboratory tests. Second, two commonly used laboratory specimen shapes namely; cylindrical and cubical, were tested to determine which shape produced the least variation of data and reproducible strength values. Third, four loading rates within the static testing range (Le. 0.007 MPa/s (1.0 psi/sec), 0.07 MPa/s (10 psi/sec), 0.34 MPa/s (50 psi/sec), and 0.7 MPa/s (100 psi/sec)) were used to determine an ideal loading rate. Finally, the number of test samples required to produce strength data within the acceptable standard deviation, considering coal seam characteristics were established.

Jan 1, 1996

By V. Srivastava, T. Ghosh

"Modeling and Simulation of SAG Mill has been widely used in design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. This paper attempts to characterize mill contents by solving Whiten’s first order contents based model in Matlab/Simulink environment. The parameters in the model such as breakage rate (S), discharge rate (D) and appearance function (A) were estimated utilizing process and design data collected from a gold mine operating in Alaska coupled with nonlinear parameter estimation scheme. This model is then utilized to predict dynamic response of other key operational variables such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated utilizing dynamic response data from the plant to encompass operational characteristics of SAG Mill behavior. Keywords: SAG Mill, Dynamic Modeling, Simulation, Nonlinear Parameter Estimation. INTRODUCTION Grinding in mineral industry is one the most important steps in the process of size reduction and plays a crucial role in determining the overall economics of the milling plant. Much of the efforts focused on improving the process efficiency using modeling and simulation have been practiced by researcher and engineers. However, up till now these models were simulated under steady state approximation because of their complex nature and difficulty in programming them in a dynamic framework. Steady state simulations have been successfully utilized in circuit designing, capacity planning and pre-flowsheet optimization. The maturity in steady state models is because of its applicability and regular use in steady state simulation packages such as JKSimMet, Limn, ModSim, etc. With the advent of equipment such as SAG and AG mill has been a recent shift in the simulating these models using dynamic approach. Because of the economic benefits of these devices and ability to act both as a primary grinding device and as secondary or tertiary crushing device they have gained a large popularity and are now universal to any milling plant. However, these device poses a real challenge to engineers and researchers in terms of operation and control. The major reason attributed to problems faced is because the ore constitutes the major portion of the charge in these devices when compared to ball and rod mill. This rock charge is subjected to disturbance such as changes in feed size distribution and ore hardness which results in unstable operation and frequent mill stoppages. One way to prevent this is to measure and control these external variables, however, lack of available instrumentation and unavailability of sensors to measure these variables has foiled the understanding of complete process occurring inside the mill thereby, inhibiting development of proper control system."

Jan 1, 2017

This paper provides a summary on the use of the POL YCOM high pressure grinding roll (HPGR) for increasing extraction in copper leaching. The energy-efficiency and significant hydrometa1lurgical benefits of the HPGR result in better acid-curing, higher solution application rates, improved copper extraction from various copper minerals and better recovery from high acid consuming ores. The HPGR's metallurgical features such as micro-fracturing, better liberation of disseminated and veinlet copper, increased oxygen and lixiviant penetration lead to higher copper extractions than achieved by conventional crushing. Flowsheet options, operational characteristics and applications for various copper ores are outlined.

Jan 1, 1996

By P. Hadzeriga

Ion exchange techniques have been growing fast and spectacularly in all phases of Science for the last two decades, but still its acceptance as a unit operation in Metallurgy is resisted. Mainly this is because ion exchange procedures are thought of as glamorous techniques by which only relatively expensive metals are to be recovered. Perhaps this concept comes from the early and basic marriage of uranium and other high price metals and ion exchange procedures. The general trend is that ion exchange technique requires equipment and materials which are too expensive to economically perform a chemical step whenever "cheap" commodities are produced. However, we are here presenting a means of utilization of waste hydrochloric acid by an ion exchange technique. We have studied this from the engineering and economic standpoint in a number of variations of the main procedure discussed here and we-conclude that under proper economic circumstances, the cost of the ion exchange material as well as the equipment and labor involved in the ion exchange section, is by no means unreasonable.

Jan 1, 1964

By S. B. Leonov, K. I. Popov, S. B. Polonsky

The offered technological line includes a flotation pulp air conditioner operating on the impact-mechanical effect and two column apparatuses with a descending pulp-air flow mounted in series. The technology developed makes it possible to increase considerably the valuable component in the concentrate simultaneously with a reduction in energy consumption for the flotation process. The experience achieved with the technology showed the possibility for obtaining sulphide silver-bearing ore superconcentrates with the noble metal content 2-10 times higher than that in the concentrates obtained by the conventional technology. The same results were obtained in the process of calcium-bearing boron-silicate ore-dressing.

Jan 1, 1995

By Abigail A. Myers, Michael A. Milczarek

Mining impacts to groundwater are being comprehensively regulated for the first time in Arizona with the implementation of the Aquifer Protection Permit Program. This far reaching program is one of the nation's strongest groundwater quality protection programs. Aquifer Protection Pennits (APPs) are required for almost all mining operations and will compel mining companies to pay increased attention to the potential groundwater quality impacts from their activities. All regulated mining operations will have to employ discharge control technologies and monitoring will be heavily emphasized. Technical requirements and relevant permit conditions are discussed.

Jan 1, 1991

By B. V. Close

Surface mining regulations together with mine and reclamation planning require collection of large amounts of geologic and hydrologic data for both new and existing mines. Recently developed microcomputer software facilitates the integration of this information from computer databases into ground-water flow models. The databases are used to identify areas which require dewatering and/or depressurizing and for generating contour maps of aquifer parameters. Gridded versions of these contour maps are incorporated into finite difference ground-water flow models which are used to design dewatering and depressurizing well fields and to estimate the effects of ground-water pumping and pit progression on local ground-water levels.

Jan 1, 1988

By Chi-shing Wang

The U.S. Bureau of Mines has been developing the mechanical roof pulling technique as a method for evaluating the effectiveness and the comparative advantages and disadvantages of various roof bolting systems, based on the characteristic responses of bolted nine roofs to a prescribed external loading system. Preliminary experiments were conducted in the Bureau's Safety Research Coal Mine using a 12-foot and a 16-foot-span test rig. The experiments have proved the capability of the test rigs and suggested the viability of the test method. This paper summarizes the test concept and the experimental results.

Jan 1, 1974

By Richard M. Crowell, John W. Shield

GeoBiotics has developed a biooxidation technology (patents pending) which involves coating refractory precious metal sulfide concentrates onto a support material and biooxidizing the sulfides in a heap configuration. The concentrates are produced from low or high grade sulfidic refractory ores or existing mine tailings. The process has been found to achieve high gold recoveries asso­ciated with stirred tank biooxidation, but at the low operating and capital costs associated with whole ore heap biooxidation. Improved gold recoveries of up to 98% after biooxidation are reported for 4 representative mines or deposits. The sulfide flotation concentrates were studied using 3 and 6 in. diameter columns or 3 in. drained vats. The refractory sulfide concen­trates biooxidize rapidly in 3 to 12 weeks with substantial increases in subsequent gold recovery.

Jan 1, 1996

By H. G. Linge

The Australian gold industry currently contributes some $4bpa to the national economy [l]. Some 40% of the total gold is produced in the region centred on Kalgoorlie known as the Eastern Goldfields of Western Australia. This region is the largest single centre of production with an output of some 100 tpa of gold [2]. In the Eastern Goldfields, refractory arseno­pyritic gold ore is an increasingly significant source of gold, feeding several operations utilizing bio-oxidation as the pre­carbon in pulp/leach (CIP/L) treatment process [1]. This paper desribes an alternative pre-CIP/L treatment option for use in the Eastern Goldfields based on the chlorination of arsenopyrite by chlor-alkali technology [3] using the salt resources available from saline water present in abundance in the region.

Jan 1, 1995

By Nick Karlin

Dragados USA is constructing the LA Effluent Outfall Tunnel, a 7-mile, 18 ft internal diameter effluent discharge tunnel, utilizing a 21.6 ft (6.585 m) Herrenknecht Mixshield TBM. This paper highlights the means and methods used for TBM launch from a 55 ft diameter shaft excavated in wet with diaphragm wall support of excavation. This included SEM excavation of jet grout blocks for starter and tail tunnels, temporary concrete structures and steel installations, TBM sealing system, umbilical management for TBM hydraulic, electric and bentonite circuits as well as complex segment delivery logistics. The many launching challenges were overcome thanks to the innovative approaches from the project team.

Jun 13, 2023

By Theodore H. Eyde

The porphyry copper province of the southwestern United States and northern Mexico, is the largest copper producing region in the world. Most of the deposits occur in Arizona which now produces over 54% of the newly mined copper in the United" States. As the many recent discoveries are brought into production, Arizona's share of the nation's copper production will increase. The term "porphyry copper" as used in this paper includes all deposits of generally low grade disseminated copper mineralization amenable to bulk mining techniques. Therefore, copper deposits such as Pima-Mission, Twin Buttes, and Vekol where the copper mineralization occurs principally in the intruded rocks will be considered as "porphyry copper" deposits. Most of the deposits have been discovered since World War II, consequently, the southwest, and particularly southern Arizona is perhaps the most intensively explored area for copper deposits on earth. Most of the major natural resource companies in the United States and Canada maintain exploration offices in southern Arizona. To illustrate the success of exploration efforts, the location of porphyry copper deposits either known or producing prior to World War II are shown on figure 1 and the deposits discovered since World War II which are either in production or in the exploration and development stage are shown on figure 2.

Jan 1, 1973

By Jamal Rostami, Wei Hu

Efficient performance of EPB TBMs in clayey ground is primarily dominated by the flow capability of the excavated muck in the cutterhead and screw conveyor. Currently, Consistency Index approach is used to evaluate clay clogging potential, but it does not include the effects of surcharge pressure on clay behavior. In this paper, a macro-scale soil rheometer is introduced to assess the clogging potential under various water content and surcharge loading conditions. The results show that, in addition to water content, surcharge pressure has clear impact on clay clogging too. In practice, Consistency Index chart can be refined to incorporate the impact of face pressure to better simulate the EPB tunneling conditions.

Jun 13, 2021

By R. K. Young

Producing a sound plant design for a major project requires hundreds of engineers and many drawings. Economical accomplishment of this task is based upon careful and orderly organization of the design team so that at all times there is a complete and workable staff but at no time a surplus of costly talent. This paper will describe the various stages in the development of plant design which normally follow the laboratory and pilot plant investigations discussed in other papers today. An outline of the procedures used in the assembling of a project design group, within an established engineering organization will be presented. Actual procedures may vary according to the size and character of the plant, the special requirements of the owner, and the make-up of the engineering organization performing the design, but most of the points covered will be found to be basic to any plant design project.

Jan 1, 1960

By L. L. Oriard

The author describes three case histories of fracture-control blasting demonstrations. This is a technique in which the walls of blast holes are scribed or notched in order to enhance the development of blast_induced fractures, and to control their direction. One demonstration was that of a tunneling application in a rock that was generally competent but strongly foliated, hence strongly anisotropic. P second test was conducted for perimeter blasting of a structural excavation in a massively jointed limestone. A third field test was conducted for tunneling through an old concrete structure. Increased applications are envisioned with new tool modifications being developed at the University of Maryland.

Jan 1, 1981