Alumina and its Role in Iron and Steelmaking...

Alumina and its Role in Iron and Steelmaking Alumina is a chemical compound of aluminum (Al) and oxygen (O2) with the chemical formula aluminum oxide (Al2O3). It is the most commonly occurring of several aluminum oxides. It is significant in its use to produce aluminum metal. It is being used as an abrasive material because of its hardness. It is also being used as a refractory material owing to its high melting point. Aluminum oxide is an amphoteric substance. It can react with both acids and bases, acting as an acid with a base and a base with an acid, neutralizing the other and producing a salt.  It is insoluble in water. Aluminum oxide has a white solid appearance and is odorless. The molar mass of aluminum oxide is 101.96 grams per mole. Specific gravity of alumina is 3.986. It is insoluble in water. Melting point of aluminum oxide is 2072 deg C while the boiling point is 2977 deg C. Alumina affects the processes of producing iron and steel during the production of iron and steel. Besides alumina is a very important refractory material for the lining of furnaces and vessels in iron and steel plants. Role of alumina in ironmaking Alumina during ironmaking enters the process through impurities in the input materials mainly iron ore. Alumina affects the sintering of iron ore. The most harmful effect of alumina is to worsen the RDI (reduction degradation index) value of sinter. RDI value increases as the alumina content rises. It is seen that within a 10 % to 10.5 % CaO content range, an increase of 0.1 % in the alumina content raises the RDI by 2 points. The strength and quality of sinter deteriorate as the alumina content rises. Alumina promotes the formation of SFCA (silico ferrite of calcium and aluminum), which is beneficial for sinter strength, but the strength of the ore components is lower, since a...

Quality of Decisions and Organizational Performance...

Quality of Decisions and Organizational Performance Quality of decisions made is very important for the smooth functioning of an organization. It is a known fact that decision making is not just about selecting the right choices or compromises. Unless a decision has degenerated into work, it is not a decision. It is at best a good intention. Decisions made become effective only after they are implemented. Organizational management is required to make a large number of decisions on a continuous basis. These decisions are required to be made for the smooth running of the organization. The performance of the organization is greatly influenced by these decisions. Hence, making decisions is a matter of a huge responsibility for the management not only against the organization itself, but against their employees and other stakeholders, as well. The decision making process can be explained as a proposal considered by the management in the context of the organization and its strategic position. Alternatives, risks and potential outcomes are considered and then a decision is reached. There can also be a post audit and a feedback loop. The decision making process of the management is subject to human error as the management personnel have personalities, prejudices and a self-interest bias. Importantly, they have different attitudes to and appetites for risk. The decisions of the management are influenced by the decision making environment which consists of a unity of management’s experience, beliefs and perceptions on one side, and decision support tools and techniques on the other side. For determining the effectiveness of the decision made, the performance of the organization is normally measured on the basis of eight performance parameters. These performance parameters include (i) profitability, (ii) organizational effectiveness, (iii) continuous improvement, (iv) productivity of the processes, (v) quality of...

Mechanical Processes for Descaling of Steel Sep08

Mechanical Processes for Descaling of Steel...

Mechanical Processes for Descaling of Steel Scale is the product of oxidation which takes place during hot rolling. The oxidation and scale formation of steel is an unavoidable phenomenon during the process of hot rolling which involve reheating of steel in a reheating furnace, multi-pass hot rolling and air-cooling in the inter-pass delay times and after rolling. Scale formed during the heating of steel to rolling temperatures in the reheating furnace is known as primary scale. This primary scale is removed before hot rolling. It is usually done for producing steel products with high surface quality and for reducing roll wear. However, secondary scale continues to form on the descaled steel surface during the inter-pass delay time in the roughing and intermediate rolling mills. The colour of primary mill scale is generally bluish black while that of the secondary scale is blue.  The secondary scale gives the steel an appearance which is similar to that of a lacquer coating finish and is often mistaken for a blue coloured primer. The primary scale is composed of three well defined layers of iron oxides. Adjacent to the steel is the thickest layer consisting of wustite having an approximate composition of FeO. The intermediate layer consists of magnetite (Fe3O4) while the outermost layer is hematite (Fe2O3). The thicknesses of these layers depend on several factors linked to the rolling of the steel and the availability of oxygen at the steel surface. The layer at the surface of the steel is richest in oxygen and constitutes 0.5 % to 2 % of scale thickness. The layer at the metal surface is richest in iron and constitutes about 85 % of the scale thickness. The intermediate layer of scale constitutes around 13 % to 14.5 % of scale thickness....

Limestone and Lime

Limestone and Lime Limestone is an odorless white, grayish-white or tan material that ranges from sized stone to a granular powder. It is often described as the most versatile mineral. Limestone is the name given to any rock formed which consists mostly of calcium carbonate (CaCO3), but to geologists, limestone is only one of several types of carbonate rocks. These rocks are composed of more than 50 % carbonate minerals, generally containing the mineral calcite (pure CaCO3). Limestone is a sedimentary rock composed mainly of CaCO3. It is formed by the deposition either of the skeletons of small creatures and/or plants (organic limestones), or by chemical precipitation, or by deposition of fragments of limestone rock, on the beds of seas and lakes. Limestones are contaminated to a greater or lesser extent by the deposition of sand or clay which is the source of the impurities usually found in the limestone. Generally there is a difference in quality in a deposit from one layer to the next. The purest carbonates and the most suitable from the production point of view tend to be the thick bedded type. Carbonate deposits may be found in horizontal layers as deposited, or at an angle from the horizontal due to earth movements. They will vary in density, hardness and chemical purity. Limestone rocks are extremely common and make up a significant portion of the crust of the Earth. They serve as one of the largest carbon repositories on our planet. The properties of limestone make it one of the most widely used minerals. Some limestones may contain small percentage of magnesium carbonate (MgCO3). These limestones are known as dolomitic limestones. Impurities (such as clay, sand, organic remains, iron oxide, and other materials) cause limestones to show different colours, especially with weathered surfaces. Limestone may be crystalline, clastic, granular,...

Standardization and the Process of Standardization...

Standardization and the Process of Standardization There is practically no economic activity nowadays which is not outlined, whether partly or totally, by the process of standardization. The worldwide acceptance of standardization is closely related to the economic globalization and the transformation of regulatory processes at the national, regional, and international levels. Standardization helps in reducing, simplifying, and organizing matters which are apt to become diversified, complicated, and chaotic if left uncontrolled. It is the process of formulating, issuing, and implementing standards. Standardization creates value at many levels. The output of the process of standardization is the creation of standards. The development of standardization as an engineering activity was pioneered in 1793 by Eli Whitney. Standardization of screw threads by Sir Joseph Whitworth dates back to 1841. Other instances of early standardization can be found during the emergence of the railway industry. Mass production became possible only through standardization. By the turn of the 19th century, standardization was already recognized in industrialized countries as a powerful tool to increase productivity through interchangeability and reduction of variety. The early part of the 20th century saw the establishment of several standardization organizations, which turned standardization into an organized and ongoing effort for industrial applications. By 1928, national standards organizations had been established in 16 industrialized countries. After the First World War, standardization, through reduction in variety, was established as a useful management tool for reducing costs. Some three decades later, seller market conditions, which prevailed for some time after the Second World War, put consumer interest under threat. To safeguard this interest and to meet the rising demand for standards for finished products, standardization activities increased in various countries, with the additional support and involvement of government and industry Definitions of standardization The standardization process is often...