Selection of Proper Refractory Materials for Energy Saving in Aluminium Melting and Holding Furnaces

Refractory lining of an aluminum melting and holding furnace are engineered with a primary design objective to keep the furnace condition stable throughout the life of the furnace. In consideration of energy saving, ideally all the heat added to the furnace should be used to heat the load or stock but in practice, a lot of heat is lost in several ways. Energy input to metal output depends on factors apart from energy losses through the furnace wall i.e. through flue gas, moisture in fuel, hydrogen in fuel, opening of furnace door. These heat loses can be differentiate as, wall losses at steady state operating condition and heat storage loss during transient condition. Practically apart from flue gas loss, majority of the heat loss took place during the transient condition. Heat loss through refractory wall during steady state condition depends on thermal conductivity, resistance against thermo chemical attack from aggressive liquid aluminium and its alloy and resistance against mechanical wear. High porosity, low thermal conductive materials due to lower strength and lower resistance towards chemical attack reduce life of the furnace and in contrast high density refractory materials needs multilayer backup to save potential energy loss through the refractory wall. This paper discusses the proper selection criteria and best suitable solution of refractory materials for aluminium Melting & Holding furnace which can contribute potential energy saving.