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By Ronald J. Thomas

Prior to 1974, bauxite-producing countries were poorly informed about important aspects of the bauxite/alumina/aluminium industry. This placed them at a disadvantage in negotiations over the development of the industry with interested parties. Since the formation of IBA, its member governments have acquired a fuller awareness of the structure and operation of the industry. The role of IBA is to enlarge the relevant information base of member governments, to act as a forum for the exchange of information on the industry and to form a focal point for multilateral discussions on problems in the industry with corporate interests and with governments of consuming countries.

Jan 1, 1984

By Felicia F. Peng

Using a fuzzy logic controller, a signal applied on the processes may be generated through a linguistic protocol expressing an operator's intuitive control strategies. In this work, fuzzy logic controller and PID controller imposed upon the feedback liquid level control systems for a stirred tank are studied and compared. The construction factors including the shape of membership functions, number of fuzzy variables, number of inputs, number of rules, and different defuzzification methods are considered in design and formulating the fuzzy logic control strategies and algorithms. From the analysis of the strategies and control performances, an optimum controller may be generated by making use of the best combination of these fuzzy construction factors.

Jan 1, 1997

By L. J. Jansen

Techniques utilized to incorporate geological data in computer modeling and ore reserve estimation have undergone considerable evolution during the past fifteen years. Computer analysis and evaluation of two precious metal deposits are presented as examples of innovative computer techniques developed at Asarco. The first is a gold deposit occurring in a steeply dipping Pre-Cambrian greenstone sequence. The second is a manto-like manganiferous silver deposit occurring in a relatively flat sequence of Late-Paleozoic sediments. In both deposits, four sub-horizontal zones of geological influence are evaluated.

Jan 1, 1985

By R. D. Hagni

Pyrometallurgical products from lime roasting of refractory gold ores, pyrite, and arsenopyrite have been examined for their mineralogy, porosity, permeability, retention of contaminant sulfur and arsenic, and potential effectiveness of gold extraction. Cathodoluminescence microscopy, supplemented by X-ray diffraction and scanning electron microscopy-energy dispersive analysis study, has shown that the products phases have characteristic cathodoluminescence properties as follows: anhydrite (CaS04), deep blue; unreacted portlandite (Ca(OH)2), deep purple; oldhamite (CaS), light yellow to rarely pink or orange; a sulfur-rich, arsenic-poor phase, violet; an arsenic-rich, sulfur-poor phase, non-CL. Within the temperature range examined (400-850°C), hematite exhibits greater porosity and permeability at the intermediate roast temperatures of 600-650°C.

Jan 1, 1993

By W. F. Hahnert, T. L. Ward, K. E. Stoll, P. A. S. Ralston

Fuzzy logic is well suited to the control of non-linear, time-varying, and/or any system for which it is difficult to obtain an exact mathematical model. To design a good fuzzy controller, a thorough understanding of the desired process behavior is required. Many papers have suggested that fuzzy controllers are robust. If they are, it is reasonable to explore whether or not they respond better than conventional controllers to errors in the feedback signal due to imperfect measurement or sensor degradation. It may be the case that simpler or less expensive sensors could be used in some processes. The research presented here relies on an integrated array of computer programs that model and simulate (1) the process to be controlled, (2) common feedback instrumentation, and (3) both fuzzy logic controllers (FLC's) and conventional controllers. Various types of feedback sensor imperfections are imposed upon the system, and the performance of the two controllers is compared. Each controller is tuned to its optimal performance in response to a setpoint change using perfect feedback measurement.

Jan 1, 1993

By J. A. Marts, R. C. Gilmore, Jr. Bogin, S. A. Saki, J. F. Brune, J. W. Grubb

"Most, if not all longwall gobs contain explosive gas zones (EGZs), i.e., zones of explosive methane-air mixtures that can cause – and have caused – mine fires and explosions. If the coal is prone to spontaneous combustion, oxygen penetration into the gob must be avoided. This paper summarizes the significant research findings from five years of computational fluid dynamics (CFD) modeling research conducted at the Colorado School of Mines (CSM) under funding from the National Institute for Occupational Safety and Health (NIOSH). CSM Researchers have developed CFD modeling techniques to identify where and under what circumstances EGZs can form in longwall gobs and how EGZ formation and oxygen penetration depend on the ventilation method, face and bleeder ventilation parameters, injection of inert gases and the operation of gob ventilation boreholes. Recognizing these explosion and fire hazards is an important first step in improving the safety of longwall coal mines. CSM modeling research has shown that EGZ formation can be effectively controlled by adjusting ventilation parameters, choosing the proper ventilation pattern and injecting inert gases where necessary. INTRODUCTION In a project sponsored by the NIOSH Office of Mine Safety and Health Research, researchers at the Colorado School of Mines have examined gas compositions and flows in longwall gobs in order to assess explosion and fire hazards. Since gob areas are inaccessible, researchers developed a series of computational fluid dynamics (CFD) numerical modeling tools to characterize these hazards. A variety of CFD models were developed to cover progressively sealed as well as bleeder ventilated gobs for both coal and trona mines. The explosion and fire hazards posed by EGZs in longwall gobs can be summarized as follows.• If the EGZ lies closely behind the longwall face, flames and pressures from an explosion can penetrate the shield supports and reach the active face area, creating blast trauma, burn hazards and toxic, unbreathable atmospheres. • EGZs can be pushed around inside the gob by roof collapses and cave-ins. If they get pushed out into the face area, sudden methane inundations and explosion hazards in face areas can result. • Fresh air flowing into the gob can create an explosion hazard as the gas composition in the gob moves from fuel-rich inert to explosive, creating EGZs. • Ignition sources inside the gob can be frictional ignitions or spontaneous combustion. • Bleeder ventilated gobs are surrounded on all sides by an EGZ that forms along the fringe areas between the fresh-air ventilated bleeder entries and the methane-rich interior of the gob. It is suspected that diffusion flames can propagate rapidly along these EGZ fringes if an ignition occurs"

Jan 1, 2015

By M. S. Klima, A. Simard, M. L. Turek

Laboratory testing was carried out to evaluate several devices for recovering clean coal from bituminous coal refuse material. The bulk of the testing focused on using a dense-medium cyclone to process -0.6-mm refuse material. A hindered-settling column and a spiral concentrator were also used to process nominal 1.2 x 0.15-mm material. Product yields and ash contents were obtained for all tests, while partition curves were generated for selected tests from which the characteristic performance parameters (relative density of separation and probable error) were determined. The results indicated that the dense-medium cyclone was capable of cleaning down to 0.037 mm, while the other devices were effective to 0.15 mm. Keywords: Coal recovery, Coal refuse, Dense-medium cyclone, Hindered settling, Spiral concentration

Jan 1, 2003

By M. B. Mooiman

Cyanidation of gold and silver ores by conventional mining and milling techniques has been practiced for over a century. During the past decade, heap leaching has emerged as a viable process for treating certain gold and silver ores. (1) The rapid development of heap leaching for gold and silver ores is largely a result of lower capital and operating costs and faster start-up time than that offered by conventional mining and milling. In general, these features make heap leaching an ideal approach for exploiting either small or large low-grade disseminated deposits of gold and silver considered to be uneconomic by conventional methods. The development of heap leaching technology has evolved from the operations initiated in the western United States. The basic components of a typical heap leaching operation are depicted in Figure 1. Run-of-mine or crushed ore (usually 1 to 5 ppm gold) is delivered to specifically prepared impervious pads. Alkaline cyanide solution is applied to the surface of the heap and allowed to percolate through the heap (typically 10-30 ft high). Pregnant leach solution which drains from the heap is collected and stored in tanks of sufficient size or in collection reservoirs. Gold and silver are recovered from the pregnant solution and the barren solution is recirculated back to the heaps after reagent make-up.

Jan 1, 1983

By N. Ward

The Gualcamayo Mine is located in the Andes Mountains north of San Juan, Argentina (Fig. 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 t (3.1 million oz) of gold. Crushing operations for the openpit mine are located in a 13,500-m3 (477,000-cu ft) underground cavern with a ceiling height of 22 m (72 ft). More than 3,600 m (11,800 ft) 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 4.2-m- (13.7-ft-) diameter shafts (Ore Pass #1 and Ore Pass #2) (Fig. 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 Thomas E. Garnar

Mineral sand products have been produced from beach sand heavy minerals for nearly a century. These minerals have specific gravities of 3.0 or higher and are extremely resistant to weathering. The most common economic heavy minerals are ilmenite, leucoxene, rutile, zircon, stauarolite, monazite, garnet, and the aluminum-silicate minerals. Of these, ilmenite is the most abundant. In some cases a deposit may contain only one or two economic heavy minerals whereas in others five or six may be present. Heavy mineral mining began in the late eighteen hundreds when monazite was mined for its thorium content. This was followed by mining activity on the North Florida coast just south of Jacksonville Beach - where ilmenite and zircon were first separated during the WW I (1,8). Modern heavy mineral mining began in Eastern Australia during the late nineteen-thirties and spread to the United States during World War II. It is the purpose of this paper to review the commercial heavy mineral products, their sources, and their uses.

Jan 1, 1985

By Daniel H. White

Block caving, unlike most other conventional forms of mining relies principally on the natural forces within the rock mass to fragment and transport the ore. Obviously, not every orebody can be satisfactorily mined by block caving. In the early stages of mine planning an attempt should be made to assess the benefits of the block caving system relative to others, and develop a reasonable mining concept that may be used to provide preliminary information to mine planners and financial specialists. It is the intention of this paper to outline some basic geotechnical parameters that are essential to: 1) Assessing the feasibility of block caving an orebody and 2) Providing semidetailed information relative to mine design based on drill hole and other data.

Jan 1, 1979

By C. Maltesh

Anionic conditioning of phosphate ores prior to fatty acid flotation is a very critical step that determines the eventual selectivity, recovery and hence the economics of the process. However the chemical mechanisms operating during this conditioning step are not established. Several studies have been conducted in the past to determine the mode of interaction of collectors with the phosphate fractions however these have been done on a laboratory scale using pure phosphate minerals. In order to test the relevance of the observed effects to plant practice in this work a comprehensive survey of plant practice was first conducted and then adsorption on flotation feed and francolite were studied under simulated plant conditions. Effects of conditioning energy and water chemistry as well as solids loading and fuel oil were determined. Most importantly, different adsorption mechanisms were found to be dominant under laboratory and plant conditions. In plant water, there was some physisorption of oleic acid on phosphate flotation feed and francolite in addition to chemisorption. However, in distilled water under laboratory conditions only chemisorption was detected. Fuel oil reduced the residual oleic acid in solution after adsorption, which explains the beneficial role of extender in phosphate flotation. The dissolved species in solution arising from the flotation feed or plant processing water are shown to clearly play a major role in determining the adsorption of oleic acid on the substrates. The study also specifically demonstrates the importance of conducting research tests under plant mixing conditions and plant water chemistry for the results to be useful commercially.

Jan 1, 1996

By Robert M. Dreyer

The first time that a geologist is confronted with the necessity of evaluating a lateritic ore deposit, he may feel that nothing could be easier. Why should there be any problems in making an economic evaluation of a relatively flat-lying, surficial ore body? After several hundred thousand dollars worth of frustrating work often culminating in a series of non-reproducible data - the evaluator may be a sadder and wiser man. This paper will try to illustrate why the evaluation of lateritic bauxite and nickel deposits is among the most difficult problems confronting an economic geologist - and, more especially, how this problem can be solved. Volumes have been published on descriptive and genetic studies of lateritic ores. Obviously, there is time today only for the briefest description of such an ore body. The laterite is a soil formed under tropical conditions and resulting in the concentration, within the soil zone, of certain tri-valent metals.- especially, aluminum and nickel. The soil zone is divided into two parts: (a) the true soil or lateritic zone and (b) the zone of, partially altered bed rock or saprolite. It is important to remember that, whereas bauxite generally is confined to the laterite zone, nickel deposits occur in both the laterite and

Jan 1, 1977

By Corey Vaughan

Unplanned shutdowns from abrasive wear part failure in crushers, chutes, and slurry pipe assets can cost millions in lost production and reactive maintenance. 2Censor patented sensor technology enables real time abrasive wear monitoring of mineral processing equipment, turning passive assets into smart, data driven components. Wireless sensors embedded in liners and pipework transmit wear data live to operators, allowing for predictive maintenance, safer scheduling, and optimized asset life. This paper will present global case studies showing reductions in downtime, increased throughput, and improved maintenance accuracy. The system is ready to retrofit, neutral to original equipment manufacturers, and proven across more than twelve countries in abrasive wear liners and slurry pipe applications.

Feb 22, 2026

By Dave Rogstad

The DART NC-1B Tunnel Project consists of two 5,100 m TBM excavated tunnels, a principal underground station, a partially completed future station, a surface station, and eight associated ventilation shafts and exit tunnels. This paper presents a case history of the project's construction, and will focus on six topics that give this project a unique and unusual history; the TBM excavation, two major differing site conditions, roadheader excavation, polyfiber reinforced shotcrete lining, the NATM design geometry, and a design/build type of contract.

Jan 1, 1995

By G. Reed Marchant

During the past two decades, we have witnessed the computer revolution. Like other revolutions, it has been successful in many ways; however, it has not been without difficulties. One of the areas where these difficulties have been more prevalent has been in the application of computers for the purpose of controlling industrial processes. During the early 1960's, many people naively assumed that bridging the gap between data processing and process control was a simple matter of connecting a few wires, doing a little programming, laying off most of the people and watching the plant make great increases in production as the lights on the computer blinked on and off. Unfortunately, it has not been that simple. Instead, a whole new-set of disciplines has been required to overcome the major obstacles that exist. Nevertheless, current successes are proving that the digital process control computer is here to stay, and that through the application of digital computers an attractive return on investment can be obtained in many applications.. The purpose of this paper is to illustrate some of the requirements for successful implementation of computer control systems, with particular attention to the following four objectives: First: Acquaint the reader with the general control problems so that he may more fully recognize the major requirements for successful implementation. Second: To acquaint the reader with the types of control hardware that can be considered for use in the development of control systems. Third: To discuss some of the major obstacles that must be overcome for successful implementation of computer control systems. Fourth: To discuss the systems approach in the development of control systems and to illustrate it in the implementation of an actual control system.

Jan 1, 1971

By K. H. Singh

The addition of new data and corrections can be made under the control of a simple editing session. All programs for this system are written in FORTRAN and executabe "MACROS".. After the addition of new data, the whole file Is reinitialized to update the binary file and cross-reference tables. Updating the binary file involves rerunning the initializing program. The creation of graphic plots like cross sections and plan views is menu-driven from a terminal and very user-friendly. Small files containing not more than 10,000 entries (survey and assay points) are suitable for this setup, particularly for computers with less than 2 Megabytes of real and virtual memory. The largest file processed contained 35,000 lines of survey and assay information and required 4 megabytes of virtual memory. Working with this size file slows down the time for the creation of plots and cross sections. Another independent system is more akin to a financial type of data base. It was installed in one Anaconda mine as part of the operation's inventory, warehouse, day-pay payroll, and purchasing data bases. It is a highly hardware-dependent system, in particular, IBM's CICS/VS (Customer Information Control System/Virtual Storage). This is a true relational data base that optimizes storage requirements, supports online inquiry, update, data entry, and data security. While this system has been tested and proven in accounting applications, it requires programming expertice in PL/I and other CICS utility programs. It is well suited for huge data bases (like the 35,000 lines of data), but cumbersome for small engineering files.

Jan 1, 1985

By C. McAllister, D. Preece, J. Berendzen

"The Multiple Blasthole Fragmentation (MBF) model models multiple explosive charge contributions and the effect on fragmentation of delay timing with its associated scatter for each blasthole. The model uses near-field blast vibration attenuation parameters and the ground p-wave velocity as inputs for part of the in situ rock property to model rock fragmentation. It models most blast design parameters explicitly and simulates the effect of wave reinforcement due to the interaction of simultaneously arriving waves or diminishing cooperative contribution from long delay intervals between charges within a blasthole or among blastholes. The fragmentation size is calculated at three-dimensional grid points within a blast, and the fines and oversized blocks are treated explicitly. The model takes a surveyed irregular geometry of the free face of a blast as the calculation boundary.This paper presents a case study on applying the MBF model at an openpit mine. Near-field vibration measurements from signature hole blasts were conducted to obtain the stress-wave magnitude and attenuation parameters as well as ground sonic velocity. A production blast was then monitored with the corresponding fragmentation measured, serving as site-specific inputs to the MBF model. Various blast design scenarios were then simulated to develop ones that provide better fragmentation to improve mill throughput for the mine. IntroductionThe semiempirical fragmentation models currently found in the literature (Cunningham, 1987; Lownds, 1995) cannot explicitly model contributions from multiple blastholes with varying delay intervals. Most of these models are not three-dimensional. Furthermore, these models predict an average fragmentation size within a volume surrounding a blasthole and use the average size to generate a size distribution over the volume. The percentage of fines and oversize blocks is included in the distribution. Typically, such models are inadequate for predicting fines and oversize blocks (Cunningham, 1987)."

Oct 1, 2016

By A. L. Martikainen

Booster fans increase air pressure to overcome resistance, the objective being to force adequate amounts of air through distant workings. They are used in areas that are difficult or uneconomic to ventilate with main fans alone. Booster fans are currently permitted in underground coal mines in some countries; the United Kingdom, South Africa, Australia and Canada have been defined as major users. Booster fans are not allowed in the US bituminous and lignite coal mining operations at the present time due to safety concerns. This paper presents the history of booster fan use in coal mines of the United States during the last 90 years. Changes in regulations, as well as advantages and disadvantages of booster fan use, are discussed. Research and petitions for booster fan use are highlighted in order to bring the debate into focus.

Jan 1, 2010

By David M. Kjos

Large diameter autogenous and semi-autogenous grinding mills represent the primary thrust of the expanding grinding technology. In spite of initial difficulties, large autogenous and semi-autogenous mills have reached an acceptable level of technology which provides the mineral engineer with a reliable, low cost means of ore comminution. A successful milling installation begins during the design stage of the grinding mill and the plant it is to be installed in. This is particularly true in autogenous and semi-autogenous mills. Critical mill and plant design factors should be considered while the mill and installation are still only ?paper.? Various current liner designs will be discussed ranging from lifter bar/plate to integral types. Modes of operation such as "high-low" will be considered. Liner maintenance procedures ranging from laydown area in plant design, proper mill shutdown methods, to installation and bolt tightening complete the equation to yield optimum performance possible for any particular grinding application. The objective of this paper is to discuss trends in wear materials, designs and operating practices, and provide some guidelines for good practice as we move through the 1980's. We will put together concepts that relate to the designs, materials and applications so that higher performance can be obtained by the operator for his specific application. The concepts are shown as being in series because they are dependent on each other to achieve the desired performance.

Jan 1, 1985