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By E. N. Durussel

"The Fox Mine has been producing copper/ zinc ore since 1970 at a rate of approximately one million tons per year, and until 1978all production was derived from longhole open stopes. In June 1978, a trial stope using bighole mining methods was started to eliminate the development of two sublevels between 400 level and surface. The trial proved to be successful, and bighole mining is now an accepted mining method for both stopes and pillars at Fox Mine.When production blasting was started in the first stope, the biggest problem encountered was the production of large amounts of sulphur dioxide gas as a result of secondary sulphide dust explosions. This gas generation resulted in lost production time and caused minor damage to underground installations to the blast level, and to the headframe. Sulphur dioxide generation has been noted in secondary drawpoint blasts and, on rare occasions, in drift rounds.This paper discusses the occurrence of the sulphur blasts and the practices and precautions used to prevent their reoccurrence at Fox Mine.IntroductionThe Fox minesite is located 30 miles southwest of Lynn Lake, Manitoba. With production startup in 1970, Fox Mine is owned and operated by Sherritt Gordon Mines Limited.The Fox orebody occurs as a large lenticular zone of semi-massive sulphides approximately 1,500 feet long and 15 to 100 feet wide running east and west. Dipping 70 degrees to the north, the orebody tends to bottom out at the 3200-foot level and reaches to within 15 feet of surface."

Jan 1, 1981

By Yue hua Hu, Wei Sun, Pan Chen, Li Wang, Runqing Liu, Central South University

"The flotation separation of muscovite from quartz was investigated using mixed sodium oleate/dodecylamine (NaOL/DDA) collectors. The flotation experiments were conducted on single minerals and their collecting performances were studied by means of adsorption amounts and molecular dynamics simulation. Flotation results show that muscovite presents good floatability while quartz exhibits poor floatability in alkaline condition. Adsorption amounts show that both NaOL and DDA can absorb onto surfaces of muscovite and quartz in presence of mixed surfactants. Molecular dynamics simulation indicates that DDA plays an important role in the adsorption of mixed surfactants on these two mineral surfaces. The molecules of mixed NaOL/DDA are arranged in a rigid and well-ordered packing on muscovite (001) surface. Only a few DDA adsorb on quartz directly, and rest DDA and NaOL molecule exist near by the quartz surface, forming a hydrophilic cylinder-like structure. This study may provide guidance for the flotation mechanism and application of mixed anionic/cationic collectors.INTRODUCTIONIn the past decades, there has been an ever-increasing demand for muscovite (KAl2(Si3Al)O10(OH)2) because of its potential applications in cosmetics, construction and metallurgy industries (Barlow & Manning, 1999). Besides, muscovite is an important carrier for some rare metals, including vanadium, titanium and lithium (SsuerrN, 1979). Quartz (SiO2) occurs as the main gangue mineral in muscovite ores, which results in a low purity of muscovite and limits its wide applications. Therefore, there is an urgent need for the beneficiation of low grade muscovite ores. Many studies remove quartz by screening and gravity separation in virtue of their differences in shape, hardness and density. However, these methods undergo poor efficiency in case of small particle size (below 50µm) of muscovite and quartz (Liubakka, Sullivan, Lamphere, Corradi, & Dykhuis, 2011; Santos, Franca, & Ogasawara, 2011)."

Jan 1, 2016

By B. L. Dorey

"Performance management is a systematic, practical approach to managing people. It is founded on some basic assumptions about people and is designed to focus on people in the work place. Organizing meaningful information and using it to involve people is a cornerstone of this system.Some common sense practices are developed to involve people in an organization's effort to improve performance. The successful implementation of this program requires solid commitment and total involvement from all levels of supervision and employees for maximum results and lasting impact. All levels of supervision participate in training sessions to tailor the systems for implementation in their areas. This style of management is data-oriented and the bottom line of success is to measurably improve performance. Basic Assumptions about PeopleMost people in an organization, regardless of level, take pride in their work and generally want to do a good job. When performance falls off, there is usually some explanation other than the employee not really caring. People like to know their exact responsibilities and clearly what is expected of them. People like to know where they stand with the boss and would like to be evaluated on what they do and accomplish, rather than on what others think or feel about them. Further, people like to be rewarded for their good results, indeed, to understand what motivates people, we must look at what happens as a result of their actions. Another belief is that supervisors often have a greater influence on the performance of their people than they fully realize. Simply letting people know how important their performance is can have an impact. The Key ElementsGiven these basic assumptions and beliefs about people, some common sense practices have been systematically developed to manage more effectively."

Jan 1, 1989

By C. Díaz, A. D. Dalvi, C. E. O'Neill

"Roast-reduction smelting (RRS) of nickel concentrate, combined with flash smelting of copper concentrate, was one of the process options that Inco considered as a means of meeting its 1994 sulphur dioxide abatement target at its Copper Cliff operations. RRS involves deep roasting the nickel concentrate in fluid bed roasters. The roaster off-gas is treated in a sulphuric acid plant, and the low sulphur calcine is reduction smelted with coke in an electric furnace to yield a sulphur-deficient matte. The latter material is converted to Bessemer matte in Peirce-Smith converters, with minimal evolution of sulphur dioxide, and the converter slag is reverted to the electric furnace. Excellent nickel and cobalt recoveries (Ire obtained. This paper discusses the development of RRS, including extensive commercial scale testing at Inco's Thompson Smelter, and its key operating parameters. IntroductionReduction of sulphur dioxide emissions has been a long-standing endeavour at Inco. At the company's Ontario Division, as shown in Figure 1, sulphur dioxide emissions were reduced from about 2 million to 685 000 tonnes per year over the period 1970-1985. Most of this impressive improvement was the result of a sustained research effort which led to increased rejection of pyrrhotite from the ore during milling while maintaining an acceptable nickel recovery. Between 1970 and 1985, the combined grade of the separate nickel and copper concentrates feeding the Copper Cliff Smelter increased from about 10070 to about 'lIJ0J0 Cu +Ni and the combined S/(CU +Ni) ratio decreased from about 2.8 to 1.65."

Jan 1, 1994

By D. L. Marchioni

"The detection and quantification of the degree of weathering is an important aspect of coal exploration and mining. Tests for weathering which are suitable for the exploration camp should be fast, simple, and require minimal equipment and operator expertise. In this study, two tests which fulfill these requirements were evaluated using samples of Western Canadian coals. These tests, one based on the pH of a coal slurry and the other on the flotation of coal in a water/diesel oil mixture, do not appear to give consistent results and are not recommended as ideal weathering parameters.IntroductionThe weathering of coal results in a deterioration of those properties which render it suitable for use in industrial processes. Consequently, the detection and quantification of the degree of weathering is an important aspect of exploration and mining. Frequently, decisions related to the depth of the weathered zone must be made at the exploration camp and, therefore, tests for weathering which are fast, and require relatively inexpensive and portable equipment and minimal operator experience, would be very useful. The aim of the study reported here was to evaluate two tests used by U. S. Steel Corp. to detect coal weathering and which satisfy the requirements for use in an exploration camp. The study is a continuation of a more extensive examination of the detection of coal weathering by various methods, reported elsewhere (Marchioni, in press)."

Jan 1, 1981

By T. Abu Leil

A new class of ternary Mg-Sn-Ca alloys is being developed to address the dual demands of corrosion and creep resistance at service temperatures. While tin has proven to enhance the corrosion resistance, calcium is expected to significantly increase their creep resistance of binary magnesium alloys. Their effects in ternary magnesium alloys are not yet known. The series of alloys studied has Sn and Ca in the ranges 3-6% and 1¬2%, respectively. The results indicate that these alloys have two-phase structures with CaMgSn phase dispersed in a matrix that is predominantly a solid solution of magnesium. The corrosion behavior of these alloys has been investigated by means of salt spray tests and potentio-dynamic measurements. Creep behavior of these alloys was measured at a temperature of 135 C under an applied compressive stress of 85 MPa. Scanning Electron Microscopy with Energy Dispersive X-ray facility and X-ray Diffraction techniques were used to characterize the microstructures. The results indicate the prospect of designing alloys that can provide optimum combinations of corrosion and creep resistance by adjusting the relative compositions of Sn and Ca in the system.

Jan 1, 2006

By N. Fukatsu

The recent development of galvanic cell-type hydrogen sensor for molten copper was outlined. The principle of the sensing mechanism, the fundamental structure of the sensor, and its performance as a process control device are discussed based on experimental work undertaken by the authors. Besides sensors based on usual perovskite-type proton conducting oxide, those using magnesium-doped alpha alumina, which was recently known as a proton conductor, were investigated and the results at the laboratory scale are reported. Considering the excellent sensitivity at high temperature and the stability to the disturbance from the attendant oxygen activity, magnesium-doped alpha alumina was regarded to be a superior material for the sensors used for such purposes.

Jan 1, 2007

By X. Cao, B. S. Naik, D. L. Chen, P. Wanjara

AZ31B-H24 Mg alloy sheets with a thickness of 2 mm were friction stir lap welded (FSLWed) at two tool rotational rates of 1000 and 1500 rpm and two welding speeds of 10 and 20 mm/s. The tensile behavior of the FSLWed AZ31B-H24 Mg alloy was then evaluated at low (-40°C), room (25°C), and high (180°C) temperatures. It was observed that the failure load increased with decreasing tool rotational rate and increasing welding speed. The maximum failure load occurred at a tool rotational speed of 1000 rpm and a welding speed of 20 mm/s at all temperatures tested. It was also noticed that at the high test temperature, the samples failed along the sheet interface, i.e. shear fracture. At the low and room temperatures, the samples failed on the advancing side (AS) of the top sheet near the interface between thermo-mechanically affected zone (TMAZ) and stir zone (SZ). The different modes of fracture observed are associated with the hooking defect.

Jan 1, 2014

By M. Isac, R. I. L. Guthrie, S. Ge

The Al-Mg-Sc-Zr alloys have shown exceptional potential as structural materials for transportation applications. These alloys have proved to be good candidates to be processed as thin strips via the Horizontal Single Belt Casting (HSBC) process. The HSBC process is a near-net-shape casting technology, which involves casting molten metal directly into thin strips, close to the final product thickness, at high cooling rates. It offers an efficient, economical and environmentally-friendly approach to the production of metal strips. Fluid mechanics and associated heat transfer are important aspects of any casting process, and the novel HSBC process is no exception. Three dimensional Computational Fluid Dynamics (CFD) simulations using ANSYS FLUENT 14.5 were performed, in order to assess the importance and effects of the various operational conditions of the HSBC process. This enabled process parameter optimization. Numerical predictions were validated against experimental casting results.

Jan 1, 2014

By K. Fumimura, T. Nishimura, M. Kohno

When applying numerical techniques to problems of deformation of rocks, the body to be analyzed is divided into small portions and is represented by a system of points linked together with the neighboring points. In the so-called distinct element modeling, the particles in the system are directly connected by springs and a contact law is used to specify forces on the particles to simulate the mechanical behavior of the body. The relation between the spring stiffness and commonly measured material properties, such as the Young’s modulus and the Poisson’s ratio, should be known a priori. For the general case of a random packing of particles, the relation is found by means of a process in which a system of particles and set of parameters are prepared to simulate a set of specimen-size test and then the input parameters are chosen to match the measured material properties. The validity of the numerical result is only demonstrated by comparison model behaviors with the measured responses. The process includes trial-and-error manner, therefore, no model is complete to reproduce the mechanical properties. In this paper, a relation between the spring stiffness and the elastic constants; the Young’s modulus and the Poisson’s ratio, is introduced to a three-dimensional distinct lattice spring method. Two simple numerical examples will be presented to demonstrate the performance of the method with the procedure for the determination of the spring stiffness.

Jan 1, 2015

By P. Espinoza, I. Yutronic, J. Olivares

"Compañía Minera Doña Inés de Collahuasi's (CMDIC) Concentrator Plant is located at 4300 meters above sea level, approximately 2000 kms north from Santiago, Chile. The concentrator has three grinding lines. Each one, Lines 1 and 2, have one SAG mill at the primary grinding stage followed by a secondary grinding and classification stage consisting of one ball mill, two hydrocyclone batteries and a sump with two pumps. Line 3 has one SAG mill (Gearless Mill Drive), followed by a secondary grinding and classification consisting two ball mills, four hydrocyclone batteries and a sump with four pumps. Average throughput for these three lines is 150 Ktons per day. Peak values of 180 ktons per day have been achieved.Since late 2008 and throughout 2009 and 2010, Operations and Automation areas developed an optimization program for the grinding process, considering the implementation of Model Predictive Controllers (MPC) for the three SAG mills, and later, extending MPC to the secondary grinding and classification stages. The implementation of a MPC solution was based on stability considerations (high variability of the SAG process, high interaction between sump level control and classification efficiency, etc), requirements for an automated and consistent operation, the need to maximize throughput under timevarying scenarios and, in the long term, optimization of grinding process considering Specific Energy Consumption, among other parameters. MPC solutions had proven control robustness and strong optimizing capabilities in terms of helping in discovering new operational points and so achieving all of the aforementioned goals.On the first stage of the program, MPC implementation considered identification of dynamical process control models based mainly on historical data, in order to know the impact of a group of Manipulated Variables over Controlled Variables. Also, the impact of measured Disturbance Variables was modeled in order to take into account the high impact and interaction of these variables over the processes. At the end of this stage, 4 controllers were successfully operating for the 3 SAG mills and the secondary grinding and classification process. In response to challenges made by the working group, the second stage of the development of control applications in the grinding process required to achieve a design and implementation of a solution capable of governing the milling process, in addition to stabilization and optimization of both processes (SAG milling and secondary grinding), to integrate from a point of view of process control and automation. Therefore, in the second stage, MPC performance was continuously monitored and optimized through advanced tuning, inclusion of more process models (with proper step tests), redefinition of specific optimization criteria and adjustment to new process needs.Finally, successful MPC implementation at Collahuasi has proved that fast development and deployment of process control solutions is possible and allows immediate process stability, higher throughput, specific energy consumption reduction, and successful product size control, among many others."

Jan 1, 2012

By Simon Houlding

"The objective of Part J of this paper is to identify the limitations of the traditional modelling methods and to illustrate, by example, the potential for error created by their application to complex deposits and mining situations. Part 2 describes the evolution of new, proven technology which eliminates these deficiencies and provides precise and practical alternatives. These promote the use of realistic geological and mining shapes and eliminate altogether the rectangular approximations of traditional methods.The Case for Precision ModellingIt is not the intent of this paper to promote the benefits of computer modelling per se. It is assumed that these are recognized by the mining industry in general. The concern of Part 1 is to identify, qualify and quantify (where possible) the limitations of the tractitional modelling methods. In many instances these methods continue to be applied to complex geological and mining situations for which they were never intended nor designed. The source and magnitude of the resulting errors, conflicts and inefficiencies are not always obvious, however, they can have far-reaching effects on the efficiency and profitability of mining operations.The conclusions support a rapidly growing demand by industry for practical, precise modelling technology which eliminates the deficiencies and can be applied with confidence to evaluation, design, planning and control of mine production in all situations. Part 2 describes new technology which has evolved in response to these industry pressures and has already been successfully applied to complex mining situations. This new technology can aptly be described as appropriate technology for the 1990s."

Jan 1, 1991

By Euler M. De Souza

"This paper presents a study developed to assess the potential use of salt tailings as backfill to control surface subsidence and as a mine bulkhead used to isolate areas of potential brine inflows. A series of index tests, centrifuge model tests and quasi-static creep consolidation tests were performed to evaluate the creep and consolidation properties of salt backfl1l and to evaluate the effect of brine inflow and brine infiltration on backfill behaviour. The centrifuge models were specifically designed to study the mechanical behaviour of salt backfill under the influence of brine inflow and long-term creep. Test results indicated that salt tailings could be applied underground as a bulkhead to seal off areas of potential inflow with the additional advantage of controlling room closure and local back instability. It is hoped that this study will assist mine planners to develop contingency plans to control brine inflow occurrences. IntroductionThe use of salt tailings as backfill is a technique that would assist in the control of potential brine inflows and surface subsidence, and would have a very positive impact on the long term adverse environmental effects associated with surface salt tailings disposal. A centrifuge testing program was designed to evaluate the behaviour of salt tailings as backfill; the effectiveness of salt backfill as a bulkhead used to isolate areas of potential brine inflow and the potential use of salt backfill to control surface subsidence. The testing program was also used to evaluate the creep-consolidation properties of salt backfill and to evaluate the effect of brine inflow and brine infiltration on backfill behaviour. This paper presents the results of the experimental centrifuge testing program and a comparison of results with models tested under I g using an electrohydraulic servo-controlled loading frame (MTS) and a creep consolidation cell. Applicability of the results to practical underground soft rock mining is also discussed.The centrifuge model tests indicated that salt tailings could be applied underground as bulkheads to seal off areas of potential inflow with the additional advantage of controlling room closure and local back instability. Because the applied stresses (1.2 MPa) and fill consolidation were relatively low, the centrifuge simulated bulkhead did not retain all of the inflow brine. At typical field stresses it is expected that the fill would be able to seal off panels with brine inflows. Further testing at higher stresses are suggested to determine the consolidation and stress levels at which the fill would completely retain any potential brine inflow head and positively act as mine bulkhead."

Jan 1, 1994

By Francis Dakubo, Courtney Young, Avimanyu Das

"Hydrometallurgy of copper ores typically involve acid leaching followed by solvent extraction and electrowinning (SX/EW). EW is the final purification stage in which a voltage is applied across two electrodes causing the copper ions to reduce and deposit on the cathode. Applied voltages are near 2 volts with current densities around 300 amps/m2. In this study, research was undertaken to decrease the energy consumed in the EW process. To do this, various cell designs were constructed and tested in which a membrane was used to separate the cathode and anode compartments with concentrated solution from SX serving as catholyte and raffinate from SX serving as anolyte. Therefore, copper in the concentrated solution would be deposited on the cathode while ferrous in the raffinate would be oxidized to ferric at the anode. Because it is assumed that ferric acid leaching is used, resulting ferric would be recycled to the leaching process. A positive side effect of the envisioned process would be the elimination of oxygen evolution at the anode and thus the prevention of acid-misting. After a cell design was selected, it was used to test a number of variables: flowrate, concentration, temperature, ion-exchange membrane, and applied voltage. Following experiments in which variable ranges were determined, statistical modeling was conducted using STATEASE software. Optimal results indicate the voltage can be decreased to 1.5-1.7 volts with current densities of 300-400 amps/m2. Significant reduction in the energy consumption was accomplished by reducing the applied voltage. Furthermore, current efficiencies and copper production rates was increased by application of the membrane.INTRODUCTIONLeaching of copper ores is achieved using mostly sulfuric acid. The copper pregnant solution is contacted with an organic solvent or resin adsorbent which picks up copper ions as in Equation 1:"

Jan 1, 2016

By H. K. Fredrickson

"Midwest Joint Venture (MJV) owns a high-grade uranium deposit in northern Saskatchewan. The deposit is located too deep below surface to be mined economically by open pit methods, and as a consequence, present plans are that it will be mined by underground methods. High-grade uranium ore of the type at MJV, encased in weak, highly altered ground and with radon-rich water inflows, has not before been mined by underground methods.The test mining phase of the project, completed in 1989, had three objectives: 1. to evaluate radiation protection requirements associated with the handling of large quantities of radon-rich water and mining highgrade uranium ore in an underground environment; 2. to investigate the quantity and quality of water inflows into the mine; and 3. to investigate ground conditions in and around the ore zone as an aid in determining the production mining method to be used.With information gained from the test mining project, a mining method for the production mine has been devised. Level plans have been drawn up, ventilation system designed, pumping arrangements made and methods of ore handling considered. All this is to be done in a manner that will be safe for those doing the work underground. Some of the mining methods planned are felt to be unique in that they are designed to cope with mining problems not known to have been encountered before. New problems underground have required new methods to handle them. Remote drilling, blasting, mucking and backfilling form the basis of the planned mining method."

Jan 1, 1992

By Yuki Tsunazawa, Sho Fukui, Chiharu Tokoro

"A milling process is one of the important unit processes in mineral processing. In the milling process, the control of particle size distribution is necessary for the later physical separation process. Since the milling process is strongly affected by the equipment designs, operation conditions and raw materials, the control for particle size distribution of milling products is mainly based on empirical rules. Recently, the discrete element method (DEM) has been widely used as an effective tool to investigate the behavior of grinding media. Although the behavior of grinding media can be accurately simulated, it is not well-established the way to predict particle size distribution after milling by the DEM simulation.The objective of this study was to develop a new method to predict particle size distribution in ball milling using the DEM simulation. To predict particle size reduction, a correlation between experiments and the simulation was investigated in various operation conditions, that is, wide range of the rotation speed and the filling ratio of grinding media. In experiments, after lime stone was ground, the average and variance of particle size distribution were evaluated using some kinds of distribution equations. In the DEM simulation, direct simulation of particle disintegration in milling process is generally very difficult because of huge computational load. Therefore, collision energy between grinding media balls orgrinding media ball and wall was used as a factor of particle disintegration.As a result, a good correlation between experiments and simulation was obtained. In addition, the particle size distribution in ball milling could be predicted using this correlation. Therefore, these results indicated that the use of the correlation between experiments and the DEM simulation was an effective approach of predicting the particle size distribution in milling process."

Jan 1, 2016

By J. W. Smith, J. G. Eacott, D. H. Napier

"Three hydrometallurgicat processes (Noranda chloride leach, B. C. Research biological leach and Sherritt-Cominco activated oxygen leach) and the Noranda pyrometallurgical process have served as the basis for design projects in the final year of the chemical engineering program at the University of Toronto. Each member of a team of five or six students devotes about 200 hours to the project and the final report is expected to include an economic analysis.None of the processes has been developed to full- scale plant, nor, in the case of the B.C. Research and Noranda processes, were pilot plant data available. Nevertheless, the designs developed provide a useful basis for a preliminary estimate of capital and operating costs and for a preliminary assessment of project feasibility.This paper discusses the approach used in the design projects with respect to engineering and economic aspects, and outlines the educational features and benefits of such a program as well as some of the problem areas that arise.IntroductionAs part of the undergraduate degree course in chemical engineering at the University of Toronto, students devote some 200 hours to a design project in their final year. Hydrometallurgical processes, not yet proven at the commercial scale, have been selected for study. The students are required to develop laboratory and / or pilot scale results into a conceptual plant design, using sound engineering principles. Capital and operating costs are then determined and a preliminary feasibility study and economic analysis are carried out."

Jan 1, 1986

By Denni Nikols

"Planning for coal beneficiation in the electric utility industry is relatively complex, involving the coordination of experts and specialists in a broad range of fields, as well as compliance with a wide variety of government regulations.This paper examines the role of the planner, reviews possible benefits of coal beneficiation, identifies potential problems and illustrates a typical planning schedule.The steps involved in the planning process are:Step I-Bench- and pilot- washability studyStep 2- Wash plant designStep 3- Power plant and boiler designStep 4-Mine designStep 5-Major environmental and technical problems to address.IntroductionElectrical utilities and coal have a long and intimate relationship . Cleaned coal is becoming an increasingly popular fuel with the utilities for a variety of reasons. Generally, the greatest impetus to burn a cleaned or prepared coal fuel comes from the need to control airborne pollutants.Long-range planning is a standard practice for electric utilities, forecasts of demand must be made well into the future. Since the lead time required to provide new facilities is often as long as 10 years and the cost very high , planning becomes an important task.For a utility that owns and directs the operation of its coal mines, the mine planning or fuel acquisition planning takes on the magnitude of other corporate planning functions. It is from this perspective that a utility would view coal preparation. Except for the interaction of a coal-fi red plant on the actual mine design the planning considerations o f a beneficiating facility for a captive mine or a contract raw coal supply are about the same. Because TransAlta Utilities is currently supplied from captive mines, this discussion will tend to focus in that direction.It is the role of a planner to plan. This is easy to say but it is not always easy to do. Often we are working within a context that resembles the geological time scale. Frequently the objectives are not clearly defined when we begin and ultimately our plans are tested in the waters of government regulations and cost benefit analyses .Planning for beneficiation of Plains coal, or any coal, provides just such a test. The planner's role in this endeavour requires a wide vision. While parts of the process may be amenable to classical methods of project scheduling, the broad range of subjects and interaction of seemingly unrelated tasks is sure to obscure some of the considerations that must be made. Therefore, the planner's chief role is coordinating the work of many experts and specialists toward the final objective.Among the specialists are combustion , geo technical, mining, civil , and mineral processing engineers , geologists, hydrogeologists, soil, and reclamation experts to list a few.When one considers coal beneficiation, the planning part o f that consideration is probably more complex than any other single engineering function. Due to the company's location in the Alberta Plains and the proximity o f the mine to the thermal generating station, this paper will tend to emphasize that situation.Beneficiation may offer some advantages over run-of-mine coal to the power plant opeator. Some of these advantages are: removal of a contaminant, power plant efficiency gains , lower plant capital costs (for new plants), possible lower mining costs."

Jan 1, 1984

By P. Mayer

"Determining the correct mechanism of a boiler tube failure is important for the prevention of future tube failures. Proper corrective measures can be undertaken to alleviate the root cause or causes for a failure only when the correct mechanism is known. A mechanism of boiler tube failure is defined as the process which degrades the tube and produces a failure.An expert system package was developed for use by electric utility power plant personnel during investigation into the cause of a boiler tube failure. It is intended to assist their efforts to recognize and identify a basic failure mechanism that can produce the type of boiler tube failure under investigation. The program guides the user to the most likely failure mechanism by asking simple questions, answers which can be obtained by determining the failure location, type of fuel, and from visual inspection of the failed tube. Expert systems are a form of artificial intelligence which imitate the decision-making process of experts.IntroductionBoiler tube failures (BTFs) continue to be the single largest source of forced outages in fossil fired electricity generating stations. Because of this a concentrated effort is being made to minimize boiler tube failure occurrences. Eliminating boiler tube failures could be worth $5 billion a year to the electric power industry(1).The aggressive service environment of fossil-fired boilers is largely the reason for these failures because the combined effects of stress, temperature, corrosion, erosion and vibration cause deterioration of boiler tube material properties and reduction in wall thickness.Determination of the boiler tube failure mechanism is important for the prevention of future problems. The root cause for a failure can be established and proper ameliorative measures taken only when the failure mechanism is identified correctly. The correct identification of failure mechanism is a complex process which may include many individuals and institutions. Technical specialists in metallurgy, chemistry, combustion, and boiler design frequently cooperate with the station staff in a failure investigation . These individuals rely on personal experience and numerous reports , theories, studies, private communications and investigations concerning the different failure modes and mechanisms."

Jan 1, 1990

By G. Bimpilas, G. N. Anastassakis

"Today, one of the most intense problems in mineral processing systems is referred to the treatment of fine (–100 µm), and even smaller size, particles. Fine mineral particles possess specific properties (small mass, high specific surface area, and high surface energy per unit area) that render their separation inefficient with conventional methods (physical, physicochemical) and equipment. As a result, it is not feasible to obtain a concentrate both of high grade and recovery in mineral value and a considerable amount of mineral fine particles is lost to the tailings. As evidence, we could cite numerous examples from industrial practice with considerable loss of mineral values to the tailings because of the fine particles size, e.g. phosphate, tungsten, tin, etc.The objective of the current paper is to investigate the possibility to separate magnetic gangue minerals and rocks (serpentine, ilmenite, and olivine) from magnesite by co-agglomerating all the gangue components and subsequent magnetic separation of the agglomerates.To meet the target, hydrophobic agglomeration tests were initially carried out on single minerals to define the favorable conditions for selective hydrophobic co-agglomeration of the gangue minerals. In this respect, the effect of the following factors was examined: pH, collector dose, conditioning time, and settling time of the agglomerates. Among the combinations examined, the most favorable proved that with amine in the basic pH region. The use of non-polar oil proved beneficial. The preliminary results were confirmed by tests on mineral mixtures. The application of magnetic separation resulted in the removal of gangue minerals and the recovery of magnesite concentrates of commercial grade (magnesite content 95% approximately) and high yield.The current paper contributes to the development of mineral processing, since it successfully copes with a very important problem of mineral processing, such as the efficient separation of fine particles."

Jan 1, 2016