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By L. Archambeault

This paper describes preliminary research on the application of Markov Decision Processes (MDP) to Real Option Valuation (ROV) and the optimisation of mine scheduling. The MDP framework is a novel approach to option valuation and scheduling in mining operations. A learning agent is introduced into the valuation process of an open pit, where prices and block ore grades have probabilistic values. The prices are modelled using a mean reverting diffusion process and the block grades using sequential Gaussian simulation. The agent is asked to learn which production parameters should be used in order to maximise the overall value of the project. The introduction of the agent permits a real option approach to mine valuation, such that the value associated with the robustness of a design to uncertainty can be measured. A simulated example is used in which there are ten blocks to be extracted under conditions of grade and price uncertainty. Using policy iteration, an optimal policy is generated and the value of production options is found. The potential financial gains from applying MDPs to mine valuation and optimisation are substantial and warrant further investigation.

Jan 1, 2007

By Chris D. Winkler

Vanadium-based sulphuric acid catalyst has been utilized to oxidize SO2 to SO3 since the early 1900?s. This versatile product displaced the expensive and easily-poisoned platinum-based catalyst in nearly all applications by the 1930?s. MECS has been manufacturing the vanadium-based catalyst since 1925 and today is the leading supplier in the world of sulphuric acid catalysts in a variety of forms. Currently, MECS has world-wide customer/technical support for the catalyst as well as a dedicated catalyst manufacturing plant in Martinez, California. MECS also has a strong technical and research and development program dedicated to creating new and improved products and services. This paper will describe some of the technical details of vanadium-based sulphuric acid catalysts as well as offering a unique look into how caesium-promoted MECS catalysts can be used in single and double absorption acid plants, and off-gas plants running on irregular gas feeds, to reduce emissions and pre-heater run times. An update on MECS technical services extended for use in characterizing converter performance is also presented.

Jan 1, 2009

By Chris D. Winkler

Vanadium-based sulphuric acid catalyst has been utilized to oxidize SO2 to SO3 since the early 1900?s. This versatile product displaced the expensive and easily-poisoned platinum-based catalyst in nearly all applications by the 1930?s. MECS has been manufacturing the vanadium-based catalyst since 1925 and today is the leading supplier in the world of sulphuric acid catalysts in a variety of forms. Currently, MECS has world-wide customer/technical support for the catalyst as well as a dedicated catalyst manufacturing plant in Martinez, California. MECS also has a strong technical and research and development program dedicated to creating new and improved products and services. This paper will describe some of the technical details of vanadium-based sulphuric acid catalysts as well as offering a unique look into how caesium-promoted MECS catalysts can be used in single and double absorption acid plants, and off-gas plants running on irregular gas feeds, to reduce emissions and pre-heater run times. An update on MECS technical services extended for use in characterizing converter performance is also presented.

Jan 1, 2009

Outotec?s direct leaching process is an atmospheric leaching process for sulphidic zinc concentrates. The direct leaching process, based on special leaching reactors developed by Outokumpu, is the most economical way to produce electrolytic zinc. The production scale applications of the process realized so far are in use at Boliden?s Kokkola and Odda zinc plants. A new full-scale application of Outotec?s direct leaching process will be started in 2008 in China. The process is integrated to the existing production plant, replacing part of the old production facilities by modern technology. Besides high zinc extraction the plant expansion and modernization offers also indium recovery, iron precipitation and solution purification processes. The process equipment includes tailor-made reactors designed on the basis of the work and experience of Outotec research center. Keywords: zinc, concentrate, atmospheric leaching, technology, indium, iron precipitation, solution purification, Outotec

Jan 1, 2008

COALTECH 2020 initiated a research project to provide the coal mining industry with a modelling tool to determine the expected types of subsidence, risks and the investment required in post-closure funds to cater for subsidence associated with bord and pillar mines. A detailed literature review was conducted to determine the most important parameters in calculating the cost associated with surface subsidence. A subsidence prediction model was developed to determine the likelihood of different types of subsidence. The study made use of current knowledge of failure mechanisms and its aim is to assist the industry and government in arriving at the most suitable arrangements when authorities require financial instruments to assure compliance with environmental regulations.

Jan 1, 2003

By W. E. Lee

Penetration and dissolution mechanisms are reviewed for predominantly single-phase oxide, two phase oxide and oxide-carbon composite refractories by liquid silicate slags. Theoretical models of these processes, as well as static (sessile drop, dipping and crucible) and dynamic (rotating finger and rotary slag) experimental tests, along with their practical limitations are considered. Direct (congruent or homogeneous) attack is controlled by the reaction rate at the slag-refractory interface or the rate of diffusive transport of species to it through the slag leading to active corrosion. Indirect (incongruent or heterogeneous) attack is controlled by diffusive transport through the slag or through a new solid phase, which forms at the original slag-refractory interface. This may lead to passive corrosion. Examples of direct and indirect attack in a range of refractory/slag systems are described highlighting the critical influence of the composition and hence viscosity of the local liquid slag adjacent the solid refractory. Penetration and corrosion can be controlled either through the local slag composition via the refractory or the bulk slag or by microstructural control of the refractory by e.g. internal generation of dense layers or external deposition/generation of passive coatings, so-called in situ refractories.

Jan 1, 2004

By M. B. Shongwe

Pt-based alloys are being developed for high-temperature applications with the aim of replacing some of the currently used Ni-based superalloys (NBSAs) in the highest temperature applications. The Pt-based alloys have a similar structure to the NBSAs, and since Pt is more chemically inert than nickel and has a higher melting point, they can potentially be used at higher temperatures, up to 1300°C, and in more aggressive environments. Several experimental Pt-based alloys were studied at Mintek, and an optimum composition was found to be Pt84:Ahi:Ru2:Cr3 (at.%). On the basis of hardness and microstructure, a later study identified a new optimum: Ptr8:A111:Ru5:Cr6 (at.%). There are at least two Pt3A1 allotropes, and the high-temperature cubic structure has better properties than the lower temperature tetragonal form, and so needs to be stabilized. This work describes the latest results obtained in transmission electron microscopy (TEM) studies of the quaternary Pt-based superalloys. These results are both interesting and important, because the samples have a higher precipitate density compared to those from earlier work. The precipitate morphology is mainly cubic, with minor areas having irregular-shaped precipitates. The high volume fraction of the precipitates is a major breakthrough, since the objective of this work is to improve the alloys. A prior disadvantage was that the proportion of the precipitates was too low in samples before this work, especially compared with the work from Germany on Pt-Al-Cr-Ni¬-based alloys as well as the NBSAs. TEM -Pt3A1 diffraction patterns were studied, and for each diffraction pattern, many possible lattice point combinations were tried, with the angle between the lattice spots as well as interplanar spacings being calculated for each phase (cubic or tetragonal) to match the measured results. An overall analysis of the diffraction results indicates that the cubic phase fitted the experimental lattice points with much lower errors compared to the tetragonal phase. Thus, with the close match achieved with the cubic structure, the structure of -Pt3A1 precipitates is likely to be cubic. X-ray diffraction has been carried out on selected samples, and the results confirmed the presence of cubic -Pt3A1 and (Pt). Different X¬ray diffractometers were used to further verify the results, and the results were also compared with those from TEM.

Jan 1, 2012

By D. J. Adams, W. K. Rymon-Lipinski

Rock engineering plays a crucial role in contributing to sustainable development in South African mining. A framework for this has been created through legislation and structures to encourage the mining industry to have a long and prosperous future. However, rock engineering input is an essential element to achieving success. The most accessible deposits have been mined in South Africa and although large reserves still remain, many of these are difficult to access and will require excellent rock engineering knowledge and skill in the future. This is borne out by the fact that more than 50 % of fatal accidents are related to rock engineering issues. Many of these may be addressed with rock engineering solutions which are not beyond current rock engineering technology. A reduction in fatalities and injuries contributes to a sustainable mining industry.

Jan 1, 2003

By M. E. Rossi

All large-scale applications of conditional simulations intend to benefit from the ‘correct’ (or’ accurate’) characterization of uncertainty, adequately describing the variability observed from the data and its impact on the final objective. This paper discusses a number of relevant issues that highlight the extent to which, in reality, a model of uncertainty is dependent on the random function model chosen. Often in the presence of large number of conditioning data most available random function models will provide similar models of uncertainty. When conditioning is scarce, the resulting models of uncertainty will vary more widely, since the final output will depend mostly on the underlying assumptions of the model chosen. The application described in this paper is taken from a large porphyry Cu operation in northern Chile, and it demonstrates the impact of several variables on the resulting models of uncertainty. In particular, some of the decisions involved include the number of conditioning data and the underlying Random Function model used (Gaussian or indicator-based). Also, implementation-specific parameters must be decided upon, such as grid size used, random number generator, simple or ordinary kriging, multiple-grid simulation, and simulation of irregular three-dimensional bodies (as opposed to regular grids). Some practical guidelines are proposed to deal with these decisions.

Jan 1, 2003

By M. Dworzanowski

The beneficiation of fine iron ore will increase in importance in the future because most new iron ore resources will be in the form of lower grade ore deposits that will require liberation of iron ore minerals at finer sizes. Generally this fine iron ore will be beneficiated to produce a pelletizing concentrate with very strict chemical and physical specifications. In addition, because of the increasing demand for iron ore there are now more opportunities to produce by-product iron ore from mining operations producing other commodities. In the past the associated iron ore minerals would report to final tailings but now there is potential value to be realised from by-product revenue. These by-product iron ore opportunities are almost all centred on producing pelletizing concentrate. Currently pelletizing concentrates are produced mainly by various combinations of flotation and magnetic separation. The selection of the beneficiation route will depend on ore mineralogy and considerations around plant capacity and final concentrate quality. The main economic iron minerals are magnetic, haematite being paramagnetic and magnetite being ferromagnetic. This, therefore, means that magnetic separation can be applied, in principle, to all fine iron-ore beneficiation plants. While flotation has a considerable capacity advantage over magnetic separation, the real advantage of magnetic separation over flotation in fine iron-ore beneficiation is that treatment of -10 µm iron ore is possible-in flotation, the feed is deslimed at 10 µm and the -10 µm stream is considered to be final tailings, even though there is often a significant amount of contained iron ore. This paper describes a study around the recovery of fine magnetite in the form of a pelletizing concentrate. The study is based on an evaluation of an iron ore by-product opportunity from an iron oxide copper-gold (IOCG) deposit. Experiments were conducted to quantify the differences in magnetic separation performance with decrease in particle size treated. A mineralogical evaluation of all the test work products was undertaken to facilitate the interpretation of the test work results. These results were then used to propose an economically viable flowsheet for maximizing fine magnetite recovery using magnetic separation.

Jan 1, 2012

By G. Kelly

A new minerals engineering education programme is being developed in Australia which aims to provide tertiary institutions with a package of educationally sound, high quality courses for undergraduates, postgraduates and professionals. The programme is jointly funded by the Minerals Council of Australia (MCA) and the Department of Education Training and Youth Affairs (DETYA) and brings together academics from a number of leading Australian universities, each developing modules in their particular area of expertise. The University of Queensland (UQ) and the Julius Kruttschnitt Minerals Research Centre(JKMRC) are jointly responsible for modules in several areas including comminution, physical separation and circuit design and optimization. Other modules are being developed by the University of South Australia (with the Sir Ian Wark Centre), Curtin University and Murdoch University. The major challenge of the programme is to provide a high standard of education that is accessible to students who may be located at several different institutions and some of whom maybe a long distance from the primary course leader. Rather than taking existing course material and putting it ‘on the web’, the programme aims to improve on past teaching practice through creative pedagogy and the development of interactive multimedia learning resources. Communications technology is used in an unobtrusive way, and the World Wide Web is used to create a flexible, user-friendly learning environment rather than to facilitate delivery of content. This paper describes the instructional design template currently being used and results of early implementation trials with groups of local and remote students.

Jan 1, 2003

By L. Joncourt, N. Touchard, G. Pochart, C. Perdon

Worldwide, the major Manganese ores can be separated into three different types: ?Oxidized ores (MnO2): in Australia, Gabon, Brazil,?. ?Semi-oxidized ores (Mn2O3): in South-Africa, Australia,?. ?Carbonated ore (MnCO3): in Ghana, South Africa, Kazhakstan?. The other Manganese ores are less rich but can be used locally or in the neighbour countries (China, Ukraina, India?). Since the beginning of the 20th Century, Manganese has played a big role in the steel industry process average usage ratio: 9,5 kg/mt of steel). The recent grow-up of this industry has led to an increase of Manganese ores demand. In parallel, several companies have increased their Manganese ore producing capacity. In this presentation, we explain the link between the main Manganese ores characteristics and the key different factors for an effective and low cost Mn alloys production (HCFeMn and SiMn): ?Chemistry ?Size ?Reactivity Then we will point out the advantages of Comilog ore and Sintec ® usages in various Manganese alloy metallurgical process compared with the other main ores and with the local ores. Some advised formulations for the different kinds of furnaces and alloys will be also discussed.

Jan 1, 2007

By L C. Pretorius

Pipe pigging is a technique for the in situ (field) coating application, to create a seamless internal anti-corrosive lining of long pipelines. The technology originated in the cleaning of pipes, and these proven cleaning methods continue to be used today. Firstly mechanical cleaning of the pipeline is performed, using wire brush, razor back, course stud and fine wire pigs, then foam pigs, or criss cross pigs, and urethane blade scrapers to remove loose debris, wax, residual hydrocarbons and corrosion products from the pipeline. Part of the proprietary techniques and expertise is to ensure that these cleaning pigs do not get stuck Next chemical cleaning of the pipeline is performed, using repeated pig runs with detergents, solvents, acid etching, corrosion inhibitors, consecutively batched between two pigs, to ensure a clean, dry metal finish to a visual cleanliness standard of ISO SA2½. These in situ techniques were developed, 40 years ago to apply internal corrosion protection to pipes using a thin layer of epoxy based paint (50 to 100 micron). Until recently these old techniques were never improved upon. Although many thousands of kilometres of pipes were successfully coated with these thin film epoxy based paints and old application techniques, these thin paint films had problems in weld coverage, and were also unable to fill pits caused by pitting corrosion, and unable to replace metal loss caused by channel erosion. New coating material developments, revised application methods and modified pigging equipment have now made it possible to apply thick film coatings as corrosion barriers to the internals of pipes in the field, using these pigging techniques. The thick coating films can be up to 1 mm (40 mils) thick in a single coating run over long distances. The new thick film coating materials and application techniques are similar to continuous screeding, creating a far more robust seamless internal pipe lining when compared to the old technology of thin film paints. With thick film polymers the option now exists to create a structural GRP pipe within a pipe, be it steel or cementicious. It has been preferable, even necessary, to move away from the traditional epoxy paints and coatings. It was found difficult or impossible to use epoxy materials for these pipe coating applications due to the requirement for achieving a suitable viscosity with adequate hold up. In order to reduce epoxy viscosity a solvent or reactive diluent is required. This inevitably lead to solvent entrapment and poor cure characteristics in cold climates. Further mud cracking in over thick areas, the inability to extend or reduce pot life, poor control of cure time and limited resistance to aggressive or chemical environments made solvent based epoxy resins a poor choice.

Jan 1, 2006

By A. Ebrahimabadi

Roadheaders are very versatile excavation machines used in tunnelling, mine development, and mine production for soft to medium strength rock formations. Performance prediction is an important factor for successful roadheader application and generally deals with machine selection, production rate and bit consumption. Among many different parameters, brittleness is also one of the material properties related to breakage characteristics and can be used as a cuttability parameter from a mechanical excavation point of view. The main objective of the research study is to contribute the brittleness of rock excavated to construct a new empirical equation for predicting the performance of roadheaders in different material and operational conditions. In this regard, a new performance prediction model for medium duty roadheaders based on a brittleness index (BI) is presented. In this study, rock mass brittleness index (RMBI) is defined in order to investigate the influence of BI on roadheader performance. RMBI is an index which can be used to relate the intact and rock mass characteristics to machine performance. Results demonstrated that RMBI is highly correlated to instantaneous cutting rate (ICR) (R²=0.94). Moreover, through the further analysis and normalization, the pick consumption index (PCI) was introduced as a parameter having a good relation with pick or bit consumption rates (PCR) (R²=0.79). Finally, the new predictive models for ICR and PCR showed very good correlations with the actual measured values. Keywords Performance prediction, roadheader, brittleness index, mechanical excavation.

Jan 1, 2011

By T. Nghipulile, G. Dzinomwa, J. Kurasha, M. Amwaama, B. Mapani, K. Maweja, T. E. Moongo

The effect of mineralogy on the grindability was investigated using three copper ores – two sulphides and one oxide. The dominant copper minerals were identified by optical microscopy and mineral chemistry derived from SEM-EDS analysis. The sample designated sulphide 1 was borniterich, sulphide 2 ore was mainly chalcopyrite, and the oxide ore was predominantly malachite and minor azurite. The gangue minerals were identified using semi-qualitative XRD analysis. Sulphide 1 contained more than 80% (w/w) of quartz compared to about 70% in the other two ores. The Bond work indices were 13.8, 21.6, and 17.3 kWh/t for sulphide 1, sulphide 2, and oxide ore respectively. This suggested that the chalcopyrite-rich ore is the hardest, while the malachite-rich ore has intermediate hardness, and the bornite-rich ore is the softest. The brittleness indices of the ores were calculated using the chemical composition of the gangue, and a good correlation between brittleness indices and Bond work indices was observed, which highlights the importance of the gangue composition in determining the fracture behaviour of the ores. There is scope for further investigation into the relationship between ore mineralogy and comminution behaviour using other breakage characterization techniques.

Mar 30, 2023

By O. A. Olaseinde

The 2101 lean duplex stainless steel has wide potential application in storage, heat exchangers, and in the oil and gas industries. This work investigates the electrochemical behaviour of 2101 duplex stainless steel with an addition of 0.15 wt% ruthenium, using potentiodynamic techniques in 1M H2SO4 at 25º, 40º, 60º, and 80ºC. The microstructures of samples were characterized using optical metallography and scanning electron microscopy. The results showed that the ruthenium addition moved the corrosion potential of alloy 2101 to a more positive potential. All samples containing ruthenium displayed longer passive regions at 25°C and 80°C compared to those without ruthenium. Alloys without ruthenium had higher critical current density (icrit) values when compared to the alloys with ruthenium. Ruthenium additions decreased the passive current densities and inhibited anodic dissolution. At room temperature the corrosion rate of alloys with ruthenium was lower than these without ruthenium.

Jan 1, 2012

By Dhananjaya Senapati, E. V. S. Uma Maheswar, C. R. Ray

Carbothermic process of Ferro Silicon production is primarily a slag-less process. However, slag formation is observed in the regular operation as experienced by almost all the Ferro Silicon Producers in different pro-portions. The problem of slagging in the furnaces may be due to: a)Variation in the input burden charge material quality b)Fluctuations in the Carbon balance and/or c)Fluctuations in the Electrode penetrations The problem will be more severe in nature with the increase of the size of the furnace. The operation performance of the furnace gets badly affected if the slag formed in the furnace is not removed from the bath in time and to the maximum extent possible. It is, therefore, very essential to know the characteristics of the slag formed in the Ferro Silicon Furnaces, besides eliminating the very cause of formation itself; and to find the routes of draining of the same from the furnace bath effectively. This paper envisages the effects of using the LIME STONE in the Ferro Silicon Burden in stabilizing the 48MVA Furnace for improved performance and better consistency. Quality fluctuations in the available Raw Materials are compared with that of the requirements for the Ferro Silicon production. The furnace operational data is compared for 12 months period each for the period corresponding to the before and after usage of lime stone in the burden and found encouraging results in the performance. Implications of use of Lime Stone in the burden on the quality of the output alloy are also studied.

Jan 1, 2007

By A van Jaarsveld

Environmentally-friendly, safe and cost-effective technology for stope drilling has successfully been introduced at TauTona mine. It has enabled the problem of inadequate compressed air pressure and its downgrading impact on production capability to be overcome. The paper traces the development process which culminated in the conversion of the entire stoping operation at TauTona to electric drilling. Background work which took place at other mines is also described. Statistics of performance improvements are provided. 1. Introduction Holman?s Silver series and the Seco S215 were drills that had a measurable impact on the South African gold mining industry. It is too soon to say whether Hilti will join those great names. However, there is no doubt that the introduction of electric drills into the harsh and unforgiving world of deep level gold mining is a significant development. History has shown that being the first to enter a new technology is no guarantee of long-term success. The pain and suffering which accompany the birth of anything new can deplete the energy of the innovator while at the same time creating opportunities for competitors to leapfrog him. In addition to commitment and enthusiasm, the innovator must therefore also possess, or have access to stamina and resourcefulness to overcome the unexpected difficulties which will inevitably arise. All of these were needed for the Hilti project.

Jan 1, 2008

Visit to the Datsun Nissan Company's body pressing and assembly plant at Rosslyn, Pretoria, and the Claremont-Danville Tunnel on 27th February, 1970. The excursion arranged for the 27th February to the Datsun Nissan motor car assembly plant at Rosslyn, near Pretoria, in the morning and the Claremont-Danville tunnel in the afternoon was well supported by some 43 members. The visitors were met at the factory by Mr Rademeyer, the Industrial Relations Manager, and members of his staff and were taken to the artisan training centre for light refreshments. There is a well-equipped training section with an air-conditioned lecture hall; we were told that such training facilities were important because of the cosmopolitan nature of the artisan staff. The visitors were divided into small parties and taken to the tool die and jig-making section, which is perhaps the key department for a factory of this nature. There the many dies for the presses in the body pressing section, as well as the complicated jigs for body welding are made. The technique for making the castings for the dies is interesting. A polystyrene model of the casting is embedded in moulding sand. In a neighbouring foundry molten metal is pressed into the headers and burns away the polystyrene, which leaves no residue, and this exactly fills the space occupied by the model. This rough casting is then machined in large copying machines (costing as much as Rl80 000). An exact plastic model of the surface of the pressing required, set up in juxtaposition to this casting is traversed by a master stylus which operates the slave milling cutter, thereby machining the surface to close tolerances. The machined casting is cleaned up by hand and finally finished in large spotting machines, using a blue dye to show up high spots, to the fine degree of accuracy required. The body pressing section was next visited. There the large number of pressed parts which make up a vehicle body are pressed out of special deep drawing steel plate. Some of the largest presses were capable of applying a pressure of 1 200 tons and cost as much as Rl85 000 each. The visitors then followed through to the assembly section where jigs are used to hold together the many pressings, which are then spot welded into body frames. The frames go to an assembly line where they are finished to the stage for painting. The continuous crawl painting assembly line carries the frames through all the stages of prime coating with zinc phosphate sprayed on in a tunnel, followed by immersion of the lower parts in a priming bath, then drying and spray painting and baking in tunnels. The body frames, after painting, join another assembly line, where the doors, upholstery and many fittings are attached. After this stage the completed bodies are lowered onto and attached to the chassis units which are largely assembled from imported parts (engines, transmission units, etc.). From the end of the line the completed cars are driven off to the trial track and then pass through a tunnel with powerful water sprays to detect leaks in the body work. The proportion of locally made parts is just on 45 per cent. An interesting aspect of the assembly organization is that, of the 140 or 160 cars completed each day there may be included some of each of the Datsun model as well as some Renault and Alfa Romeo models models which are assembled by this company. The change from one model to another several times a day does not present any difficulty to the organization. Each section of the assembly plant 'buys' the units from the preceeding section and 'sells' to the succeeding section. This means that the responsibility of each section ends when the unit is sold to the next section. The cost of repairing any faults found subsequently is charged to the section where it is found, which puts a powerful emphasis on meticulous inspections between sections to safeguard their costs. After the tour the parties assembled at the lecture hall where a lavish cold buffet luncheon was provided by the company. After luncheon Mr A. R. C. Fowler, on behalf of the Institute, thanked the Managing Director, Mr W. J. Wilson and his staff for this most interesting and well organized visit. The party then left for the Claremont-Danville tunnel. The tunnel is being driven by General Mining Federale Kontrakteurs through the Daspoort Range, Pretoria, to link the suburbs of Danville, near Iscor, and Claremont, which at present can only be reached by a nine mile detour. It is estimated that some 6000 vehicles per day will use the tunnel. Before entering the tunnel a short talk was given by Mr Ross who is in charge of operations. He called on various officials and staff of the Consulting Engineering firm, Basil Read (Pty.) Ltd., to describe the tunnel and

By Luthie Els, Chris Coetzee, Roedolf Koekemoer, Casper Els, Olof Vorster, Frank Fereday

Three electric arc furnaces (EAFs) were constructed by Union Carbide at Tubatse Ferrochrome (TFC) in1975. This plant was expanded to four furnaces at the East Plant in 1985 and the gas cleaning system was enlarged without taking flow dynamics into consideration. In order to improve competitiveness, TFC has increased furnace capacity, partially substituted coal for coke, and changed the charge mix. These changes increase the heat and dust load into the air pollution control (APC) system. TFC embarked on a project to improve the APC capacity by: ?Quantifying the required off-gas capacity ?Optimising the aerodynamic flow through the system by means of Computational Fluid Dynamics (CFD) ?Converting the old Brandt Koyo top entry baghouses to bottom entry ?Upgrading the cleaning system ?Installing Gore-tex® ePTFE membrane filter bags The estimation of required off-gas capacity is traditionally done by rule-of-thumb methods such as specific extraction. A more elegant evaluation method was developed for simulating the effects of changes in charge mix on the furnace reaction gas volume and the APC system. Reaction gases are calculated by modelling the reactions taking place in the furnace and off-gas volumes are compared to both fan and baghouse capacity. This enables identification of bottle-necks in the off-gas system. CFD techniques were utilized to evaluate geometric imbalances and propose solutions to ensure optimal use of off-gas capacity. The system modifications were completed over several months and the modified equipment went into service in May2006.

Jan 1, 2007