Induction Furnace Refractory Lining with Silica Ramming Mass...

Induction Furnace Refractory Lining with Silica Ramming Mass Induction furnaces are used for melting cast iron, mild steel and various alloy steels in foundries and making of steel in mini steel plants using sponge iron. Lining is the important part of induction furnace. Furnace performance is directly related to the performance of its lining. Well laid and stabilized lining results in smooth working of furnace, optimum output, and good control of the metallurgical reactions. The lining practice best suited to a particular furnace depends upon the capacity and design of the furnace, operation practice adopted during making of a heat, and furnace output. For successful and consistent performance of the lining, the important aspects are (i) use of proper grade and quality of the lining material, (ii) careful and systematic lining practice, and (iii) consistency in working conditions.  Fig 1 shows the installed refractory lining of a coreless induction furnace, Fig 1 Installed refractory lining of a coreless induction furnace The characteristics of the lining material needed for consistent lining life include (i) thermal characteristics which means that it has to withstand the stresses developed by thermal cycles during the furnace operation, (ii) chemically inert to metal being melted, (iii) structural strength under operating conditions, (iv) high erosion resistance, (v) ease of installation, (vi) reparability of the lining, (vii) ease of dismantling, and (viii) economics. As such, it is very difficult to judge the suitability of a particular lining under various conditions like operating temperature, metal being melted, the type of formed slag, and furnace capacity. Chemical inertness to the liquid metal can be achieved by using acid and neutral lining for the acidic slag and neutral or basic lining for the basic slags. Normally, the selection of refractory for the furnace lining is...

Refractories and Classification of Refractories...

Refractories and Classification of Refractories Refractories are inorganic, nonmetallic, porous and heterogeneous materials composed of thermally stable mineral aggregates, a binder phase and additives. The principal raw materials used in the production of refractories are normally the oxides of silicon, aluminum, magnesium, calcium and zirconium. There are some non-oxide refractories like carbides, nitrides, borides, silicates and graphite. Refractories are chosen according to the conditions they face during their use. Some applications require special refractory materials. Zirconia is used when the material is required to withstand extremely high temperatures. Silicon carbide and carbon are two other refractory materials used in some very severe temperature conditions, but they cannot be used in contact with oxygen, since they oxidize and burn in atmospheres containing oxygen. Refractories are the materials which are resistant to heat and exposure to different degrees of mechanical stress and strain, thermal stress and strain, corrosion/erosion from solids, liquids and gases, gas diffusion, and mechanical abrasion at various temperatures. In simplified language, they are considered to be materials of construction which are able to withstand high temperatures. Refractories are usually inorganic non-metallic materials with refractoriness greater than 1500 deg C. They belong to coarse-grained ceramics having microstructure which is composed of large grains. The basis of body is coarse-grained grog joined by fine materials. Refractory products are a specific sort of ceramics that differs from any ‘normal’ ceramics mainly with their coarse-grained structure being formed by larger grog particles joined by finer intermediate materials (bonding). ASTM C71 defines refractories as ‘non-metallic materials having those chemical and physical properties that make them applicable for structures or as components of systems that are exposed to environments above 538 deg C’. Refractories are to be chemically and physically stable at high temperatures. Depending on the operating environment, they...