Properties and Uses of Ironmaking slag...

Properties and Uses of Ironmaking slag The majority of iron in the world is produced in the blast furnace (BF) and hence BF slag represents the largest quantity of ironmaking slag produced around the world. The BF is the primary means for reducing iron (Fe) oxides to molten, metallic iron. It is continuously charged with Fe oxide sources (ore, sinter, and pellet etc.), fluxes (limestone, and dolomite), and fuel (coke, and coal). Liquid iron collects in the bottom of the furnace and the liquid slag floats on it. Both are periodically tapped from the furnace. BF slag is defined by the American Society for Testing and Materials (ASTM). It defines BF slag as the non-metallic product consisting essentially of silicates and alumino-silicates of calcium and other bases which is developed in a molten condition simultaneously with iron in a BF. The slag consists primarily of the impurities from the iron ore, mainly silica (SiO2) and alumina (Al2O3), combined with calcium (Ca) and magnesium (Mg) oxides from the fluxes. Sulphur (S) and ash which normally come from coke and coal are also contained in the slag. Slag comes from the furnace as a liquid at temperatures of around 1500 deg C. It is a man-made molten rock, similar in many respects to volcanic lavas. Chemical and mineralogical composition of BF slag Chemical analysis of BF slag normally consists of four major oxides namely (i) SiO2, (ii) Al2O3, (iii) calcium oxide (CaO), and (iv) magnesia (MgO). These oxides make up around 95 % of the total quantity. Minor elements which are present in the slag are Fe, S, manganese (Mn), alkalis, and trace amounts of several other elements. Common composition range of various components of BF slag is given in Tab 1. Tab 1 Range of...

Management Development...

Management Development The development of executives in an organization is necessary for its present smooth functioning as well as for its proper functioning in future. The development of the executives takes place along two lines (Fig 1). The first consists of enhancing his knowledge towards technologies and technological skills which are changing very fast in today’s environment. The second consists of developing his managerial abilities so that he can function in higher managerial positions ably and in a responsible manner. Fig 1 Two lines for development of executives In the present day environment it is necessary for every organization to give serious thought to the development of its executives in various management techniques. The performance and the efficiency of the executives are greatly enhanced if they are well versed with the techniques of management. Hence the organizational management is required to give importance to the management development activities. Basic organizational decisions need an increasingly long lead time. Since no one can foresee the future, management cannot make rational and responsible decisions unless it selects, develops, and tests the executives who are to take care of these decisions in future, since these executives are going to become managers in the coming future and are going to run the organization. The executives need to have managerial abilities. They need to have along with the theoretical knowledge, the ability to organize and to lead. They need to know how to make decisions and what the managerial control techniques are. Management development programs develop the executives of today into efficient managers of tomorrow. These programs ensure continuity in the organization, which is a vital aspect for the efficient running of the organization, especially in a large organization where this need is more essential. The organization being a wealth...

Theory and Practice of Sintering of Iron ore Nov25

Theory and Practice of Sintering of Iron ore...

Theory and Practice of Sintering of Iron ore Sintering of iron ore is a generic term which is used to describe the process whereby a sinter mix (raw mix or green mix) of iron ore fines, fluxes, fuel (coke breeze) and plant return fines (e.g. mill scale, blast furnace dust, and returned sinter fines etc.) are converted into a particular form of agglomerate. It consists of heating the sinter mix with a particle size of less than 10 mm to such a temperature that surface of each grain of the charge mix starts to melt and the formed melt creates liquid bridges between grains, which, after solidification, ensure formation of a solid porous material called sinter having a screened size normally of 5 mm to 30 mm (upper size can go upto 50 mm to suits local requirements), and which can withstand operating pressure and temperature environment inside the blast furnace (BF). The process of sintering is a thermal operation involving melting and assimilation reactions. The first stage of the sintering process is the formation of the melt which involves the reaction between fine iron ore particles and fluxes. The initial melt is generated from adhering fines during heating via reaction between iron ore and fluxes. Then, nucleus particles are partially assimilated or dissolved into the primary melt to form more melt. Before complete melting is achieved, the sintering temperature drops due to the short residence time at the maximum temperature and then the melt solidifies and mineral phases precipitate, resulting in the formation of the bonding phases. During the sintering process, the chemical reactions are taking place at high temperature and the iron ore and fluxes are combined together and form a sinter cake composed of iron ore, silico-ferrites of calcium and aluminum...

Properties and Uses of Steelmaking Slag...

Properties and Uses of Steelmaking Slag Steelmaking slag is an integral part of the steelmaking process. It is produced during the separation of the liquid steel from impurities in steelmaking furnace and is a non-metallic by-product of steelmaking process. It occurs as a molten liquid melt and is a complex solution of silicates and oxides which solidifies upon cooling. It primarily consists of silicates, alumina silicates, calcium aluminum silicates, iron oxides and crystalline compounds. During steelmaking, slag is produced in the hot metal pretreatment processes (desulphurization, desiliconization, and dephosphorization etc.), in the primary steelmaking processes (basic oxygen furnace, electric arc furnace, and induction furnace), slag formed during the secondary refining processes (this slag is sometimes called ?secondary refining slag? or ?ladle slag?), and slag formed in tundish during continuous casting of steel (also known as tundish slag). The slag generated in the basic oxygen furnace (BOF) and electric arc furnace (EAF) is of basic nature while the slag is of acidic nature in induction furnace because of the use of silica ramming mass as the lining material. Since most of the steel produced in the world is by BOF and EAF processes, hence slag from these processes is discussed in this article. The processing of the steelmaking slag (Fig 1) is normally carried out by (i) solidifying and cooling of the hot liquid slag, (ii) crushing and magnetic separation treatment of the slag to recover the scrap, (iii) crushing and classification of the slag for grain size adjustment to manufacture the slag product, and (iv) aging treatment of the slag product for improving its quality and volumetric stability. These processes are explained below.   Fig 1 Processing of steelmaking slag As steelmaking slag is formed, it is in a molten or red-hot state at...

Planning for Organizational Future...

Planning for Organizational Future Future is always unpredictable (Fig 1), though it is an important aspect for planning for an organization. Future can be described only by two things namely (i) it is not known in the present and only people can make a guess about it, and (ii) it is going to be different than what exists today and from what is expected now. Fig 1 Unpredictable future The above statements are not principally new or particularly unusual. But these statements have far-reaching following implications. If present day actions and commitments are based on the predictions of future events then these are wasted attempts. The best thing which the people can hope to do is to anticipate the future effects of the events which have already permanently taken place. But it does not precisely mean that because the future is going to be different and cannot be predicted, people continue to function in the present way with the comfortable assumption that nothing is going to change. Though it is risky to make the unexpected and unpredicted future, still it is a normal activity. And it is less risky than sailing along on the comfortable assumption that nothing is going to change and also less risky than following a possibility of ‘what must happen’ or ‘what is most probable’. Management is required to accept the need to work systematically on making of the organizational future. But this does not mean that the management can work for the elimination of risks and uncertainties since this is not feasible. The one thing the management can try to do is to find, and occasionally to create, the right risk and to exploit uncertainty. The purpose of the work on making the future is not to decide what...