Electric Arc Furnace Cover Refractories
The main damages reasons of electric arc furnace cover are: strong thermal shock, high temperature dust corrosion, low melting point high iron oxide dusts corrosion, thermal stress between liquid phase sintering layer and non-sintering layer, electric arc radiation caused molten corrosion and thermal stress.
Earlier, burned high alumina bricks are used at small electric arc furnace cover, but the service life is not long. In recent years, unburned high alumina bricks and high alumina precast blocks are developed and electric arc furnace cover life is significantly prolonged.
High power and ultra high power electric arc furnace steelmaking proportion is increasing, steel smelting tempo is accelerating, therefore, electric arc furnace cover suffers more intense thermal radiation, thermal shock and dusts corrosion. So burned high alumina bricks can meet production requirement, furnace cover triangle zone is constructed by corundum castable, chrome alumina castable, corundum magnesia castable and precast blocks. The surrounding of triangle zone is built by sintered high alumina bricks, unburned high alumina bricks, magnesia bricks and magnesia chrome bricks.
High Power & Ultra High Power Electric Arc Furnace Cover Refractories
| Item |
Burned magnesia chrome bricks |
Sintered magnesia chrome brick |
Fused magnesia chrome ramming mass |
Chemical bonded high alumina ramming mass |
| Applications |
Outside triangle zone |
Outside triangle zone |
Triangle zone surrounding |
Triangle zone surrounding |
Triangle zone surrounding |
| MgO % |
58 |
57 |
60 |
/ |
/ |
| CaO % |
2 |
1.2 |
1 |
0.2 |
0.2 |
| Fe2O3 % |
14 |
13 |
11.5 |
1.5 |
1.5 |
| Al2O3 % |
6 |
6.5 |
5.5 |
83 |
82 |
| Cr2O3 % |
19 |
21 |
20 |
/ |
2.0 |
| SiO2 % |
/ |
/ |
/ |
10 |
10 |
| Bulk density g/cm3 |
3.24 |
3.26 |
2.90 |
2.93 |
2.93 |
| Apparent porosity % |
<18 |
<18 |
/ |
/ |
/ |
| Crushing strength Mpa |
>30 |
>30 |
30 |
35 |
35 |
| Refractoriness under load ℃ |
1700 |
>1750 |
/ |
/ |
/ |
| Linear change rate %(1500℃,3h) |
±0.2 |
±0.2 |
±0.5 |
0.4 |
0.4 |
| Item |
Chemical bonded chrome corundum ramming mix |
Chemical bonded chrome corundum castable |
Corundum casted precast blocks |
Chrome corundum casted precast block |
Corundum spinel castable |
| Applications |
Triangle zone |
Triangle zone |
Triangle zone |
Triangle zone |
Triangle zone |
| MgO % |
/ |
/ |
/ |
/ |
8 |
| CaO % |
/ |
2 |
2 |
2 |
1 |
| P2O5 % |
3 |
/ |
/ |
/ |
/ |
| Cr2O3 % |
9 |
3.0 |
/ |
3.0 |
/ |
| Al2O3 % |
87 |
95 |
97 |
95 |
90 |
| Bulk density g/cm3 |
2.93 |
2.93 |
2.95 |
2.95 |
2.95 |
| Apparent porosity % |
/ |
/ |
18 |
18 |
18 |
| Crushing strength Mpa |
80 |
35 |
50 |
70 |
70 |
| Linear change rate %(1650℃,3h) |
0.4 |
0.4 |
0~0.5 |
0~0.5 |
0~0.8 |
Factors Affecting Furnace Cover Service Life
The power of electric arc furnace. With the application of ultra high power electric arc furnaces, electric arc intensity and thermal radiation intensity are increased, furnace cover suffers stronger thermal shock and sintering shrinkage, meanwhile, flying dusts also increases, the corrosion of furnace cover is severer.
Furnace cover water cooling area. To prolong furnace cover life, water cooling area is larger and larger. Electrode surrounding area is not easy for water cooling, so there should adopt high grade refractory products.
Electrodes water cooling. Spraying water to electrode can significantly reduce electrode consumption and triangle zone refractory materials service life.
Operation. Electric arc furnace cover opening and closing times can greatly affect service life. Meanwhile, smelting temperature, smelting time, oxygen blowing strength and so on all have great influence on furnace cover life.
