LECTURE 9 Refractory Materials NPTEL（9的耐火材料NPTEL讲座）.pdf

LECTURE 9 Refractory Materials Contents: Role of refractory What is a refractory? Why required? Refractory requirements Melting point of some pure compounds used to manufacture refractory Properties required in a refractory Types of refractory materials Insulating materials Key words: Refractory, steelmaking, furnaces Role of refractory Refractory materials have a crucial impact on the cost and quality of steel products. The diversification on steel products and their cleanliness requirement in recent years have increased the demand for high quality refractory. Steelmaking requires high temperatures of the order of 1600 degree centigrade. In addition steelmaking handles high temperature phases like molten steel, slag and hot gases. These phases are chemically reactive; refractory materials are required to produces steels. High quality refractory at a cheaper cost is the main requirement because cost of refractory adds into the cost of product. What is a refractory? Refractories are inorganic nonmetallic material which can withstand high temperature without undergoing physico – chemical changes while remaining in contact with molten slag, metal and gases. It is necessary to produce range of refractory materials with different properties to meet range of processing conditions. The refractory range incorporates fired, chemically and carbon bonded materials that are made in different combinations and shapes for diversified applications. Why required? • To minimize heat losses from the reaction chamber • To allow thermal energy dependent conversion of chemically reactive reactants into products because metallic vessels are not suitable. In steelmaking, the physico- chemical properties of the following phases are important: Slag: Mixture of acidic and basic inorganic oxides like SiO , P O , CaO, MgO, FeO,etc.; temperature varies