Bulk Raw Materials Handling and Blending Techniques of Sinter Plant: A Case Study of Ajaokuta Steel Company Limited, Kogi State, Nigeria

Bulk raw materials handling plant and sintering plant preparatory plants are established to receive, blend, stockpile, prepare and supply specified grades of raw materials for smooth operations of iron making plant (Blast furnace), steel making plant (Basic oxygen converter) and lime Plant(calcinations plant). The study discusses bulk raw materials handling and some general problem of scientific analysis and documentation of basic equipment details, stockyard facilities, bulk materials transport systems and sinter processes, for the general knowledge and operational procedures of these plant for effective and efficient operational processes for optical results. Iron ore concentrate supplied from the mines to some extent fluctuate in their chemical composition as a result of the nature of the deposit with various factors controlling beneficiation processes and addition of metal-bearing materials collected as a waste product from the Rolling Mills, Blast Furnace and Sinter Plant which must be recycled through Iron ore concentrate stockyard. The part of the sinter mixture is melted at a temperature about 1300-1480 ° C and a sequence of reactions shaping the sinter cake to be loaded into the blast furnace to produce iron from a pig

A Fundamental Study into the Use of Different Ferrous Ores on Melt Characteristics of Sinter

Steelmakers are becoming more motivated to use iron ore resources with a wider range of grades and mineral types that were previously considered unsuitable or uneconomical for sintering. In this respect, specific issues which now require further investigation and understanding include the sintering of ores with a) overall higher gangue content, b) elements that cause problems in the steel manufacturing operations, and/or c) distinctive sintering performance compared with traditional hematite-rich iron ores. Laboratory-based investigation of the sintering performance and the behaviour of gangue impurities during sintering is an important step towards the successful utilisation of these resources in steelmaking. To explore the feasibility of small-scale sintering pot testing, a ‘millipot’ facility (diameter of 53 mm and height of 400 mm) was established and used to examine the sintering performance of iron ores and other non-traditional ferrous materials. The sintering performance of a millipot was examined across a range of operational conditions (coke rate and suction pressure) and compared with an industrial sinter strand operation. Tablet tests were also performed to assist in the design of the millipot experiments and identify conditions for achieving mineral composition similar to the industrial sinter. For the millipot experiments, the materials used need to be compacted to increase the bulk density, and a higher coke rate is required to compensate the high heat loss caused by wall effects. A higher suction pressure is also necessary to maintain an oxidising atmosphere in the sinter bed. As expected, it was not possible to completely eliminate the wall effect, which results in more primary hematite at edges of the sintered column. Heavier compacting at the periphery of the column can minimise the wall effect. The sintered material from the centre of column simulates industrial sinter reasonably well. As such, millipot provides a practical technique to evaluate the sintering process and material performance at laboratory scale, helping to bridge the gap between tablet sintering and large scale pot sintering, or full scale plant trials. The results of millipot testing can be used for designing larger scale experiments or commercial sintering trials..

Investigating Rapid Concrete Repair Materials and Admixtures

This dissertation presents a literature review of the state-of-practice for the use of IC in concrete mixtures and how structural engineers and construction engineers can adapt IC to their present and future work. Current high early strength concrete mixtures have natural cracking and shrinkage problems due to the high content of cementitious material or their chemical components. Using IC allows for early strength, enhanced durability, reduced shrinkage and a better curing by providing water that can be absorbed by the cement past after the final set. Rapid hydration and high early strength Portland cement and calcium sulfoaluminate (CSA) concretes are commonly used as pavement repair media. The fresh properties (slump, setting time), mechanical properties (elastic modulus, compressive and tensile strength), and volume stability (autogenous shrinkage, drying shrinkage, restrained ring shrinkage, and creep) of rapid repair media were evaluated with and without internal curing with saturated lightweight aggregate. Significant improvements in volume stability were also noted. Results indicate that internal curing can successfully improve volume stability and mitigate restrained shrinkage cracking in rapid repair media without compromising fresh properties or ultimate mechanical strength. Maturity was observed for CSA mixtures and exhibited a correlation with compressive strength development which could be beneficial for rapid repair media on the field

Annual Report 1973-1974

It contains the statement of R&D works undertaken, achivement made and the expenditure by the laboratory during the financial year 1973-1974

Experimental and Numerical Studies of Burden Layers at Blast Furnace Charging

The blast furnace (BF) is the main production unit in the processing of iron ore to molten iron (“hot metal”) in the steelmaking industry. It is a large process with huge throughput and energy consumption, so even a slight improvement of its efficiency can lead to considerable reductions in costs and harmful emissions. The charging system is the only way by which the initial distribution of the raw materials can be controlled. This distribution not only determines the structure of the arising burden bed, but also the chemical and thermal efficiency of the gas. These are crucial factors for achieving a low rate of reductants, a long life length and a more sustainable operation of the furnace. Focusing on the behavior of particles forming heaps and layers in granular systems, this thesis has studied some questions related to burden-layer formation, burden bed properties, burden descent and gas flow distribution in the blast furnace throat and shaft. Firstly, the effects of particle shape and physical parameters on the porosity and angle of repose of iron ore particle heaps were simulated by discrete element method (DEM). Models of non-spherical particles (cylinders and cones) were established using the sphere-cluster method. For comparison and model validation, small-scale experiments were undertaken with particles of the same shapes prepared in the laboratory. The consistency of the simulated and experimental results demonstrate that the established DEM model can be used for the prediction of the porosity of a particle system. Some key physical parameters of the main burden materials (pellets, sinter and coke) were measured and validated by experiments. The experimentally determined parameters were the Young’s modulus, Shear modulus, Poisson’s ratio, particle density, coefficient of restitution, as well as coefficients of static and rolling friction. The experimental and calculated results were found to exhibit good agreement, which confirmed that the measured DEM parameters were of sufficient accuracy to be used in simulation of the burden distribution and descent in the blast furnace. DEM models describing the porosity distribution and radial ore-to-coke mass ratio of the burden layers in the blast furnace shaft were successfully established based on a bell-less burden charging system with 2D slot and 3D sector throat models. An experimental bell-less charging system with a scale of 1:10 compared to an industrial BF was designed and operated in a set of experiments. DEM simulations of the corresponding system showed results in general agreement with the empirical findings, validating the numerical models. Two kinds of non-uniform descent of burden in the upper part of the blast furnace were considered in a numerical DEM-based model, where the descent rate in the furnace center is greater than the descent rate at the wall or vice versa. The results showed that the ore-to-coke ratio decreases where the burden descent rate is low and increases where the descent rate is high. Finally, the effect of intermittent charging on the thermal and flow conditions in the upper shaft was analyzed by Computational Fluid Dynamics (CFD) combined with DEM. A model of the counter-current flow of gas and solids and the temperature of the two phases in a simplified setup was developed. The results clarified how the temperature and velocity of the ascending gas are affected by the intermittent charging.Masugnen är den huvudsakliga processenheten vid produktion av råjärn för stålframställning. Den är en industriell reaktor med mycket stor genomströmning av material. Ugnen har en hög energiförbrukning, vilket innebär att redan små relativa förbättringar i driften kan har stora implikationer för material- och energiåtgång samt för de utsläpp som förorsakas av processen. Masugnens chargering, d.v.s. inmatningen av det fasta råmaterialet vid toppen, är av stor betydelse för styrningen av råmaterialets radiella fördelning i ugnens övre del. Chargeringen bestämmer beskickningens struktur imasugnsschaktet, vilket påverkar ugnens termiska och kemiska verkningsgrad. Dessa faktorer är centrala för att uppnå driftpunkter med låg förbrukning av reduktionsmedel, lång ugnskampanj samt en hållbar järnframställning. Föreliggande avhandling studerar beteendet hos partiklar som bildar högar och lager i granulära system. Avhandlingen behandlar frågor av speciell relevans för bäddens egenskaper i masugnsschaktet, där lager av olika beskickningsmaterial bildas vid chargeringen och efter det långsamt sjunker nedåt i ugnen. För att beskriva hur gasen fördelas i schaktet måste även porositeten hos materialbädden vara känd. I den första delen av arbetet studerades inverkan av partikelform och fysikaliska parametrar på porositeten och rasvinkeln för högar av järnbärare. Systemet simulerades med diskreta element-metoden (DEM), där partiklar med annan form är sfärisk skapades genom att klumpa ihop överlappande sfärer (eng. sphere-cluster). För jämförelse och för validering av den matematiska modellen utfördes småskaliga laboratorie-experiment med partiklar av samma typ. Överensstämmelsen mellan de simulerade och experimentella resultaten visade att DEM-modellen kan användas för att prediktera porositeten hos partikelsystemet. Några viktiga fysikaliska parametrar hos de huvudsakliga beskickningsmaterialen (pelletar, sinter och koks) uppmättes och validerades med hjälp av experiment. De parametrar som bestämdes experimentellt var elasticitetsmodulen, skjuvmodulen Poissons konstant, partikeldensitet, restitutionskoefficienter, samt statiska och rullnings-friktionskoefficienter. De experimentella och simulerade resultaten befanns överensstämma väl, vilket bekräftade att DEM-parametrarna som bestämts var tillräckligt noggranna för att kunna utnyttjas vid simulering av beskickningsfördelning och -sjunkning i masugnen. DEM-modeller som beskriver bäddporositetens och den radiella malm-koksfördelningen hos beskickningen i masugnsschaktet skapades för ett system med s.k. Paul Wurth-chargeringsmål med två- eller tredimensionella modeller för masugnens gikt. Ett experimentellt klocklöst (eng. bell-less) uppsättningsmål i laboratorieskala i 1:10-skala jämfört med en industriell ugn byggdes och utnyttjades i experiment. DEM-simuleringar av motsvarande system gav resultat som generellt överensstämde med de experimentella resultaten, vilketvaliderade de matematiska modellerna. Två typer av ojämn sjunkning av beskickningen i schaktet studerades även numeriskt med hjälp av en DEM-modell, där bädden simulerades sjunka snabbare eller långsammare i masugnens centrala del. Resultaten visade att malm/koks-förhållandet avtar i regioner där bädden sjunker långsamt, medan kvoten ökar i regioner där sjunkhastigheten är hög. I arbetets sista del studerades hur en satsvis chargering påverkar det termiska och flödesmässiga dynamiska tillståndet hos den översta delen av masugnsschaktet med hjälp av flödessimulering (eng. Computational Fluid Dynamics, CFD) kombinerad med DEM, s.k. CFD-DEM-teknik. En förenklad och nerskalad modell utvecklades, som beskriver motströmsflödet av gas och beskickningsmaterial och temperaturerna hos de två faserna. Modellen klargjorde hur temperaturerna och gashastigheten påverkades av den oregelbundna chargeringen, vilket förklarar fenomen som man kan observera vid ugnstoppen i den verkliga driften av masugn

Proceedings of the Scientific-Practical Conference "Research and Development - 2016"

talent management; sensor arrays; automatic speech recognition; dry separation technology; oil production; oil waste; laser technolog

Développement durable et les industries du ciment et du béton

Le développement durable c'est un moyen d'atténuer les dommages à l'environnement du passé, d'ajuster le consumérisme frénétique actuel, de diminuer les écarts sociaux entre les nation dans le but de léguer aux générations futures une société plus juste dans un environnement plus salubre. Jusqu' à présent seuls les changements climatiques ont attiré l'attention du public, mais le développement durable c'est beaucoup plus que cela. Seulement 20% de la population mondiale bénéficie d'un niveau de vie élevé et consomme la plus grande partie de l'énergie et des matériaux exploités, et par voie de conséquence, génère la majeure partie des émissions de C02, le gaz à effet de serre responsable des changements climatiques. En même temps 50% de la population mondiale gagne moins que $2 US par jour, cette population a un grand besoin d'hygiène, d'hôpitaux, d'écoles, de maisons juste pour vivre avec un minimum de dignité. Dans un tel scénario les industries du ciment et du béton peuvent jouer un rôle primordial pour résoudre une partie des problèmes sociaux et atténuer le fardeau environnemental. L'industrie du ciment est souvent montré du doigt comme une industrie particulièrement polluante, même si elle n'est responsable que de 6$2 US a day gasping for sanitation, hospitals, schools, houses just to satisfy the minimum of dignity. In such a scenario the cement and concrete industries can play a key role either for solving social problems as for helping to mitigate the environment burden. Cement industry is often focused as a polluting industry, responsible for 6% of world CO2 emissions, and concrete is frequently presented as a low technological added value product that generates around 1 billion tonnes of wastes per year. This is a common unfair perception that reveals a lack of information and adequate analysis. The cement industry experienced an extraordinary reduction in gas and dust emissions as well as energy saving rooted in significant technological investments in the seventies and eighties. Its CO2 emission is much lower than that of other industrial segments, such as transportation and progresses continue. At the same time millions of tonnes of industrial by-products and wastes generated by other industrial sectors are consumed and valorized by the cement and concrete industries every year. As a construction material, concrete fulfils almost all the social and technological needs of societies. The spectrum of available concrete ranges from some MPa to 800 MPa, exhibiting high flowable properties or low noise when casting, showing good thermal performance at low cost, evidencing the immense technological progresses achieved in recent years. With the current available technology a much longer life cycle of concrete structures should be achieved. An infrastructure lasting longer will contribute to reduce waste generation and alleviate budgets to invest in other social requirements instead of"indefinitely paying" for rebuilding or repairing structures in benefit primarily of contractors."--Résumé abrégé par UMI

Proceedings of the Scientific-Practical Conference "Research and Development - 2016"

talent management; sensor arrays; automatic speech recognition; dry separation technology; oil production; oil waste; laser technolog