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By John G. Watson, Judith C. Chow, Richard T. Egami, Daniel L. Freeman

A methodology for apportioning ambient PM-10 (particulate matter) concentrations to sources is described and applied to PM-10 concentrations in the vicinity of a large gold mining operation. With this methodology, samples representative of particulate sources such as desert overburden, diesel equipment, milling operations, road surfaces, and others are collected and analyzed to derive chemical source profiles. Ambient 6-hour PM-10 samples collected downwind from the mine are analyzed and used with the Chemical Mass Balance model to apportion ambient PM-10 among the various sources. In an example application, primary contributing source types are found to be desert overburden and diesel equipment. Relative contributions vary according to time of day, with diesel equipment frequently being the dominant contributor during nighttime periods.

Jan 1, 1991

By J. A. Herbst, K. N. Han, P. B. Queneau, S. W. Asihene

As hydrometallurgy matures as a technology, more of its existing process knowledge will continue to be summarized in the form of detailed mathematical models. This development is happening at a time when major improvements in computer hardware have reduced the cost of computing. The opportunity then exists, through the solution of these process models, to design, control, and optimize hydrometallurgical plants on the basis of the physics and chemistry of its processes and less on empiricism. In this paper, a review of the current capabilities of sensors and phenomenological models for selected hydrometallurgical processes is presented. Future trends, in terms of the control and optimization of hydrometallurgical plants, are then explored. The possibility of simultaneously optimizing plant design and associated process control system performance is discussed.

Jan 1, 1993

By D. J. McKee, D. M. Wiseman

The usefulness of simulation as a technique for metallurgical process design and optimization studies has been greatly extended over the last few years by the development of a number of general purpose simulation packages. The packages, or simulators, all have the common objective of presenting the mathematical models and simulation methods in a form which is readily usable by plant engineers and metallurgists. To date, most simulators have been concerned with steady state simulation, but packages capable of dynamic simulation are now becoming available. The paper outlines the essential features of versatile steady state and dynamic simulators. Typical applications are presented by considering examples of design and optimization studies. Limitation on the use of simulators are also presented.

Jan 1, 1991

By F. L. Jackson

When using perlite as an insulation, it is important to determine the requirements for different applications as this influences the processing of the perlite. In cryogenic application, perlite properties of low density and fine particle size are desirable, while loose fill insulation applications require similar properties and water repellency. However, in perlite insulating concrete applications, a coarser particle, of higher density, is required to provide improved compression strength. The essential properties of perlite including particle size, density, and surface treatment are discussed in relation to the various insulation applications. Also, typical mineral processing and manufacturing techniques are reviewed.

Jan 1, 1987

By Oscar Letelier Gonzalez

The goal of mine planning is to determine "the best" strategy to exploit an ore deposit during its workable life. Such strategy must be consistent with the objectives of the company and must be subject to the contraints imposed by economical, physical and geological conditions. Mine planning process may be broken down into three categories, according to the planning horizon: Long range, Short range and Operational. The shorter the scope of planning, the higher the level of details and the lower the degree of freedom associated to each plan. A long range plan defines the economic limit of mining at the mining life end of the deposit; it also can be used as an aid in the evaluation of the economical potential of a mineral deposit and as a guide for short range plans.

Jan 1, 1979

By Thomas J. Martin, James W. Martin, Paul F. Martin

The conveyor belt is the basic building block of a broad range of material handling applications in modern mining systems. The mining plans and site conditions dictate basic system requirements but this is only a part of total design evaluation. The total system in the typical mining situation can encompass all the activities from the excavators at the mining face to the processing plant, site loadout facilities and/or a power plant. The number of alternative configurations which must be evaluated including subsystems and components is limited only by analytical time and creativity. The constraints and issues which must be addressed continue to expand, driven by reliability, environmental impact and cost competitiveness. All of the system requirements must be translated into specifications for costing, final design and construction.

Jan 1, 1993

By Thomas R. Kuesel

All engineering designs are based on assumptions regarding the behavior of the structure or facility being designed. These assumptions may be based more or less heavily on theory, but are credible only if verified by observations of field performance. Dr. Peck's "State-of-the-Art" paper has described the semi -empirical process of soft ground tunnel design, emphasizing the importance of records of field performance of actual projects constructed under a variety of conditions. This paper will present the principal results obtained from measurements made during construction of the soft ground tunnels for the San Francisco Bay Area Rapid Transit System. SCOPE The BART System comprises 75 route miles, including 14 miles of soft ground tunnelled subways in San Francisco, Oakland, and Berkeley. All tunnels are single-track sections, approximately 18 feet in diameter. Usually there are two parallel tunnels at the same level, but under Market Street in San Francisco there are four tunnels (two over two), and there is also a three-track section (two over one) in Broadway, Oakland.

Jan 1, 1997

By Randy Ynchausti

ERIC GUTIERREZ, Knowledgescape: Our next speaker is Randy Ynchausti. He's the director of development, Knowledgescape systems division, of EIMCO Process Equip- ment Company. The title of Randy's talk is "An Expert Control System for Phosphate Beneficiation." RANDY YNCHAUSTI: System integration. How does the systems integrator survive when caught between plant engineers, plant management, and third-party engineering firms, and stay within the budget of the corporate goals? I'm not sure that anyone knows how to do all of that on one project. Results are critical when we talk about how systems integrators work with operating people, how the operating people want systems integrators to work with them, and how both groups work together so that at the end of a project, you have been provided with solutions that meet your needs and solve your problems at a fair price. How does the integrator's role change when working with different types of professionals, such as plant managers, plant engineers, engineering firms, or other system integrators? Finally, what is the dynamics of people working with machines and providing services and solving needs? The average number of employees per pound of copper processed has decreased significantly during the past 15 years. I would dare to generalize and say that the average number of employees per whatever unit of measure we have in whatever industry we work in has decreased over the last 15 years. From a system integrator's perspective, there are some clients who lack a bit of internal expertise as corporate downsizing occurs, and that's one reason why we go out to system integrators or third-party vendors and buy things from them to solve our problems. Downsizing really amounts to savings, but more than that, I think Brian expressed this and I agree with him, it also amounts to a cost. Unfortunately, most of us count the savings and none of us count the cost in that approach. It's easy to count the savings, which is one reason why we count it so quickly. Maybe that also accounts for why we set our pencils down so quickly after we get that dollar value. Maybe we should pick that pencil up every once in awhile and refigure the expense, the cost to us, and determine what we're going to pay during the next year or two or three in losing that expense, or that staff. A broad experience base accumulated over projects at various plants helps system integrators to provide services to clients. This experience enables the system integrator to

Jan 1, 1998

By William Petruk

Performance assessments are carried out to monitor operations, to evaluate performance and to identify processing problems. The assessment involves collecting and analyzing representative samples from critical points in a flowsheet and interpreting the data. Sample analysis techniques include chemical analyses, mineralogical investigations, mineralogical analyses, and materials balancing. Chemical analyses provide the lowest cost assessment and should be used liberally, particularly in monitoring a process. Materials balances performed on chemical assays for a suite of samples are used as a first step in evaluating a process. Mineralogical investigations are more expensive than chemical analyses but need to be used only at the beginning of mining and metallurgical operations and as a second step in assessing processing problems. Quantitative mineralogical analyses combined with materials balancing provide the most complete performance assessment, but the procedure is expensive. On the other hand, the assessment has the potential of a large payback when carried out where warranted.

Jan 1, 1991

By Osamu Shoji, Mamoru Kato

In order to continue improving the quality of telecommunication services to meet the expectations of the people and to increase reliability in the case of emergency such as disasters, Nippon Telegraph and Telephone Public Corporation (NTT) is now constructing cable tunnels which connect main urban telephone offices. However, almost all the large cities in Japan are built in river deltas, so that their chief underground features are low strength fluvial deposit and a high ground water level. In this saturated soft ground, the ground surface at an installation site has occasionally subsided through deep excavations for cable tunneling construction. As these settlements have sometimes caused accidents, especially in densely populated large cities, NTT has made much effort to avoid such accidents. These accidents have occured mainly in flexible sheeting due to its inward movement. Therefore, after the investigation into forecast method of sheeting deflection with accuracy, NTT has reserched a system which forecasts ground surface settlements. This paper describes an outline of the ground settlement forecast system and practical example on the site.

Jan 1, 1979

By Peter C. Lighthal, Harvey N. McLeod, Iain G. Bruce

This paper describes the practical aspects of handling cyanide leach tailings. Alternative systems for cyanide destruction are briefly discussed. The provision of adequate retention time to allow natural degradation of cyanide during summer months is the most economical method of cyanide destruction. Cyanide in ground- water can frequently be both persistent and mobile, so that tailings basins should be designed to limit seepage. Common methods for limiting seepage are presented. Other aspects addressed are water balance, winter operation and abandonment of cyanide tailings systems. A case example of the Cheni Gold Mines Lawyers Creek Project tailings handling system is presented.

Jan 1, 1987

By Michael J. Martinson

Mine ventilation has been evolving as a separate field of study since the middle of the nineteenth century, and some practitioners might assert that mine ventilation has come of age as a discrete field in the last decade or two. Certainly the extensive literature now available on many facets of the subject, international congresses, the phenomenal upsurge of interest in mine ventilation in the United States of America since the passage of the 1969 Federal Coal Mine Health and Safety Act, and the existence of a virile mine ventilation society in South Africa with its own monthly journal all point in this general direction; on the other hand the lack of a rational design philosophy for ventilating mines suggests that mine ventilation may still be on the threshold of maturity. To generalise, many mines are still ventilated simply to comply with arbitrary statutory regulations, or with some ill- defined notion of reducing the risk of injury associated with the atmospheric environment in mines. Hazards in this category include oxygen deficiency, toxic gases and particulates, pathogenic gases and aerosols, explosive gases and dusts, and extreme climatic conditions. Although many mines are ventilated to abate the risk of a specific injury, there is inevitably a spectrum of latent and patent atmospheric hazards in every underground mine. The writer (Martinson, 1976) has previously drawn attention to the dearth of material on mine ventilation design in textbooks and technical journals, and to the overly simplistic approach sometimes adopted in the limited work published on the subject. The available material undoubtedly contains useful technical data and persuasive views, but seemingly could not be used to demonstrate the rational engineering approach to mine ventilation design advocated in the present paper. The range of papers presented at the 1975 and 1979 Congresses, and the diverse interests and affiliations of delegates, emphasize the multidisciplinary nature of mine ventilation. Easily recognisable topics include: Fluid mechanics Thermodynamics Heat transfer Flames and combustion Aerosol physics Radiation physics Geophysics and geomechanics Occupational diseases Epidemiology Industrial physiology Despite these heterogeneous connections there can be little doubt that mine ventilation is fundamentally an engineering field and not an off-shoot of some other branch of applied science. The distinction is important because mine ventilation has essentially developed as a form of ad hoc trouble- shooting, and in the process mining engineers have relied extensively on the assistance of experts drawn from other fields. Thus historically there has been limited scope for the application of rational design techniques, and personnel enlisted from scientific disciplines may not have had any previous experience in the intricacies of engineering design.

Jan 1, 1980

By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

Rutile ore is an important resource for the production of titanium products, and flotation is an efficient method to enrich rutile from its deposits. Motivated by strong commercial demand for titanium metal and alloys, substantial efforts have been made to improve the flotation efficiency of rutile. Styryl phosphonic acid (SPA) and salicyl hydroxamic acid (SHA) are commonly used as collectors for rutile flotation, and lead (Pb) ions can be used as activators for rutile flotation with SPA or SHA. Xanthates have a price advantage over SPA and SHA for the flotation of sulfides as SPA and SHA prices are higher than xanthate prices. In this work, we found that when rutile is activated by lead ions, amyl xanthate is an efficient collector for rutile flotation at pH 8. A slightly basic slurry can be readily obtained. Moreover, the price of amyl xanthate is lower than that of SPA or SHA. In this regard, this flotation strategy has the potential to be used in industry. Furthermore, the adsorption features of amyl xanthate on the Pb-activated rutile surface was investigated by experimental methods, which provides insight into the role of lead ions in rutile flotation.

By Dan B. Kivari

A key operation of any milling circuit is grinding. Over the last two decades, large diameter semiautogenous grinding (SAG) mills have become the preferred primary grinding mills. The drive systems became more complex as the size of the mills became larger, during which time operating and design experience for SAG mill accumulated. Considerable reliance is now placed in power electronics to provide flexibility in SAG mill operation to meet the demands of lower operating costs. Most earlier SAG mills were designed to operate at fixed speeds. Present day SAG mills can operate at a fixed speed or variable speed through the use of an ac synchronous motor or dc motor. This flexibility, however, comes with an increase in capital and operating costs. Since the capital and operating costs of a project directly affect the project's rate of return, the selection of a SAG mill and its drive system should depend, in part, on the impact that the extra cost makes on the project. This impact can be measured by performing an economic analysis based on net present cost (NPC) calculations. Although the NPC calculation is an important factor in the grinding mill selection, other factors, such as reliability of mill drives and power source, are important elements in the decision making process. This article examines how the NPC calculation, plus reliability and power source, influence SAG mill selection.

Jan 1, 1992

By Bruce W. Cavender, Brian L. Granger

The leaching characteristics of non-homogeneous ores have traditionally been difficult to assess in laboratory tests. A result of the large sample size necessary to ensure representativity, this difficulty is most acute for ores containing nuggets or other irregular occurrences of precious minerals. Consequently, small-scale leaching tests are often regarded as indicative rather than conclusive. The predictive nature of leaching tests can be improved by applying the experimental design concepts of blocking and randomization. In the case of column leaching, experimental 'blocks" are constructed with the same number of columns as there are separate test conditions. These blocks are treated identically throughout the test, with differences between columns within each block being the variables of interest. To maximize the uniformity of the blocks, randomization procedures are employed in the preparation of the sample and conduct of the test. The initial ore sample is screened and individual column charges composited from randomly selected increments from each size fraction. The leaching order, daily solution analyses, and processing of leach residues are similarly randomized. The observed differences in leaching performance between the columns in each block are compared to determine the over-all outcome of the test. A statistical analysis using t distributions gives a quantitative measure of the reproducibility of the outcome.

Jan 1, 1995

By Maria S. Adusumilli, A. Bhaskara Rao

ABSTRACT The presence of gold in lateritic crusts over mafic and ultramafic volcanogenic complexes in / and greenstohe belts, has called the attention in several parts of Brazil and also in Australia. Recent studies reveal the variety of structures and mineralogy of such crusts, and their importance in correlation with host(bed) rock types, as exploration guides, specially for greenstone belt metallogeny. The expected nature of growth of plates and/or nuggets in such crusts is under detailed study, and is considered as possibly due to dissolution and reprecipitation phenomenae of disseminated-fine-low grade ore in the host rock, in this investigation, laterite geochemistry, though incipiently discussed todate, is of fundamental importance and significance. Lateritic gold can be classified texturally as: dusty and diffused, fine, thin platy, taDular, and nuggets. Such gold is pure, and is often restricted to nodular (pisoliths, ooliths, concretions) forms or the matrix, that constitute the crusts or lateritised gravel beds which have an essentially goetnitic nature. Further this gold is recovered directly by mining the crusts or the adjoining placers with the metal derived from them. The thickness and extension of laterite crust zones is extremely variable depending oh the paleoclimatic conditions, and is conditioned to the favourable lithology and its structural expression. However, the "growth" of gold in these laterites will be conductive , without doubt, to several small scale mining activities, specially in the developing countries and regions limited to latitudes 309N and 309S.

Jan 1, 1987

By Richard Lovat

INTRODUCTION Soft ground tunnels may be above the ground water table or they may be subaqueous. The ground may be clays, silts, sands, gravels, glacial deposits, boulder tills, and any of these in any combination. Because of the relatively low strength and deformability of soils, difficulties often arise in soft ground tunnelling. These soil characteristics and resultant tunnelling difficulties, have had a direct influence on the development of "Lovat" Tunnel Boring Machines. We have been required to recognize and adapt to unusual ground conditions and to follow through with design, fabrication, and field maintenance to ensure dependable, trouble-free operation. The basic "Lovat" machine is a fully shielded, wheel-type with the cuttinghead driven by a monorace type bearing with gear drive incorporated in the bearing. Mechanical innovations have been added to the basic machine which complement the resources of manpower, equipment, and materials available to the contractor for a specific operation. FULL FACE SUPPORT The installation of hydraulically operated closure doors or flood control doors, at the cuttinghead, is one of the early "Lovat" technical innovations. Flood control doors provide full face support in running or flowing ground. In water bearing sands and silts the excavated material can

Jan 1, 1981

By Leandro Augusto Viana Teixeira, Angela Avelar, Ruberlan Gomes Silva, Virginia S. T. Ciminelli, Daniel Majuste

Rare earth elements are essential for modern life products and green technologies. Recent supply constraints have boosted the development of rare earth projects after the price peak of 2011. The feasibility of a project depends on the definition of a processing route, which in turn depends primarily on the rare earth mineral, with monazite and bastnaesite representing the two most relevant minerals. Monazite-type ores usually contain high acid consumption impurities, such as iron, aluminum, calcium, magnesium and phosphates, and may also contain prohibitive levels of radioactive thorium in its composition. Based on thermodynamic analysis, the present work discusses the fundamentals of a selective process route for rare earth extraction from monazite ores with high iron content. This process involves sulfation by means of concentrated sulfuric acid and roasting at a high temperature. The route yields high rare earth extraction with low iron and thorium extraction and low acid consumption. Rare earth extractions as high as 80 percent were achieved, while iron and thorium extractions were lower than 1 percent, and acid consumption was lower than 0.34 kg of sulfuric acid per kg of ore. The operational window was compared to the one predicted by thermodynamic modeling, with 700 °C representing the optimal roasting temperature.

By Jaye Pickarts, Bret Boster, Jack McPartland

Pegasus Minera de Chile, Ltda. is completing three phases of metallurgical evaluation on the Pullalli project to develop a preliminary process flowsheet. A project feasibility study is in progress. The feasibility study includes a proposed process flowsheet designed based on results from the multiple stages of metallurgical evaluation. Phases I and II of metallurgical evaluation included laboratory scale heap leach and milling cyanidation testwork on multiple drill core composites and bulk ore samples from the Pullalli Project. Phase Ill included pilot scale milling/cyanidation testwork on Pullalli drill core composites. The proposed flowsheet includes selective mining and separate processing of low grade and high grade ores. Low grade ore will be crushed and heap leached. High grade ore will be milled leached for 12 hours in an agitated cyanidation circuit. After 12 hours of leaching, sands and slimes will be separated and the sands will be washed using a counter current cyclone (CCC) circuit. Partially leached and washed sands will be added to the crushed low grade ore for heap leaching treatment and permanent placement. Partially leached slimes will be thickened in a high capacity thickener and will be processed in a CIP circuit. Leached slimes will be placed in a tailings impoundment.

Jan 1, 1996

By Richard L. Stein

INTRODUCTION Increasing a miner's chance of surviving a disaster requires advance planning for emergencies, adequate training of personnel, and the provision of proper survival equipment. It is extremely important that fires and toxic gases be detected early, and that warning systems such as stench, audible and visual alarms, and communications systems be provided to allow timely escape. However, situations do occur where timely warning is not provided and immediate escape is not possible, regardless of the precautions that are taken. Under such circumstances, a combination of new per¬sonal protective devices and old techniques can provide protection that is adequate to save a miner's life. SELF-RESCUE EQUIPMENT Self-rescuers are devices which provide a short-term supply of respirable air under the potentially lethal con¬ditions following a mine disaster. Functioning either as filtration devices for the elimination of carbon monoxide (CO) or as oxygen supplies, self-rescuers allow an endangered miner a limited amount of time in which to effect an escape or reach a place of temporary safety. Carbon-Monoxide Self-Rescuers For almost 50 years, filtration self-rescuers have protected miners' lives following explosions or fires. Designed to eliminate carbon monoxide from inhaled air, the first of these devices was approved in the 1920s and has evolved into the two units that are approved today-the Mine Safety Appliance (MSA) W-65 and the Draeger 810. Both of these units rely on the cata¬lytic conversion of very toxic carbon monoxide to rela¬tively safe levels of carbon dioxide (CO,). As shown in Figs. 1 and 2, both of these filtration self-rescuers operate in the same manner. On inhalation, the mine air passes through both coarse and fine filters that remove the dust, preventing the dust from coating the chemical beds or entering the miner's mouth. The air then passes over a drying agent that removes water vapor; this is required to prevent the water vapor from poisoning the catalyst. Subsequently, the dried air passes over the Hopcalite catalyst, where carbon monoxide is converted to carbon dioxide. Then, the air passes through a heat exchanger that reduces the temperature of the inhaled air. Finally, the air is inhaled by the user. Air exhaled by the user passes through the heat ex¬changer and exits the device through an expiratory valve. Both units of this type are subject to certain limita¬tions: 1) The units do not protect the user against oxygen¬deficient air; when air is inhaled through this type of self-rescuer, the device only removes the carbon mon¬oxide. If the mine air contains less than 15% oxygen, anoxia is inevitable. Symptoms of anoxia include dizzi¬ness, shortness of breath, quickened pulse, and deeper and more rapid respiration while the victim is at rest. During heavy exertion such as would be expected dur¬ ing escape efforts, a 15% oxygen level can cause loss of consciousness. 2) The units do not protect against excessive levels of carbon dioxide. Available data on carbon monoxide and carbon dioxide concentrations following explosions or fires are limited, but there are indications that the carbon monoxide concentration can rise to 2% and the carbon dioxide concentration can reach 5 or 6% of the mine air (by volume). In some situations, the in¬haled air could contain up to 6 or 7% carbon dioxide. At a carbon dioxide concentration higher than 2%, breathing patterns can be affected adversely. At a con¬centration of 6 or 7%, the effects include severe respira¬tory distress, with unconsciousness resulting from exer¬tion such as that needed for escape activities. 3) The units do not protect against high inhalation temperatures. The catalytic oxidation of carbon mon¬oxide to carbon dioxide is an exothermic reaction that evolves a large amount of heat. As the carbon monoxide concentration increases, the temperature of the inhaled air also increases. Available data show that above 1.5% carbon monoxide, the air inhaled through some self¬rescuers can be as high as 90°C (194°F). At those

Jan 1, 1982