Protection of Blast Furnace hearth lining by the addition of TiO2 Jun09

Protection of Blast Furnace hearth lining by the addition of TiO2...

Protection of Blast Furnace hearth lining by the addition of TiO2 The refractories of the blast furnace (BF) hearth is the most critical material in the iron making process by the blast furnace since the BF campaign life greatly depends on its condition. The most critical region is the transition region between the furnace wall and bottom of the hearth. The hearth refractory wear is a serious concern for many of the BF operators. The abrasive and erosive effect on hearth zone of a blast furnace are due to various conditions namely high ambient temperatures, continuous movement of the liquid smelting products, chemical activity from the products, pressure and chemical activity from the gases and entry of moisture into the BF hearth. The main reasons for the wear out of the BF hearth refractories are (i) high furnace productivity, (ii) frequency of long furnace shut downs (> 2 days), (iii) water leakage from furnace water cooling system and (iv) quality of charge materials. The wearing of the hearth refractories affects the campaign life of a blast furnace. Blast furnace operators use the following methods to decrease the wear rate of the BF hearth refractories. Lowering the BF productivity Reducing coal injection rates Grouting of the ramming mass between staves and carbon blocks Temporary plugging of the tuyeres Increasing the cooling rates of the wall Addition of the TiO2 containing materials Improvement of the lining life of the BF hearth by the addition of TiO2 containing compounds is the most widely used method. TiO2 provides protection to BF hearth lining against premature erosion. Process of BF hearth protection The addition of TiO2 containing compounds results in the precipitation of Ti (C,N) (titanium carbonitrides) onto the bottom and the walls of the BF hearth (Fig 1...