Electric Arc Furnace Cover Refractories Description
The function of electric furnace cover is heat insulating and environment protection, avoiding the diffusion of dust in the furnace. In the central zone of furnace cover, there is holes for inserting electrode and adding some metallurgical ingredients. Although electric arc furnace cover doesn’t contact with steel liquid directly, it is exposed to strong thermal shock, high temperature and dust atmosphere. Low melting point and high ferric oxide dust will react with electric arc furnace cover refractories which will not only produces liquid phase material but also contributes to surface sintering. There are great thermal stress between sintering layer and non sintering layer due to different linger change, and causes crack between sintering layer and non-sintering layer. When the temperature is above 2000℃， electric arc optical radiation, strong thermal shock and molten corrosion to furnace cover triangle zone when electrode is pulled out and inserted into furnace cover, will generate great thermal stress and contribute to further spalling of triangle zone electrode hole’s surface and underneath. It is the main reason of electric furnace cover’s damage.
Sintered high alumina bricks are usually used in ordinary power small size electric arc furnace covers. The service life of sintered high alumina bricks is generally between 60~120 times. The water cooling area of small size electric arc furnace cover is relatively small, which is a factor affecting the service life of sintered high alumina bricks. The development of unburned high alumina bricks, high alumina castable precast blocks significantly enhance service life of furnace cover, meanwhile, the construction process is simple, is labor saving and energy saving. High alumina precast block is more popularly used than high alumina bricks now.
Small Size Electric Arc Furnace Cover Refractories Physiochemical Index
Item
Sintered high alumina bricks
Sintered high alumina bricks
High alumina precast block
High alumina precast block
Unburned high alumina brick
Unburned high alumina brick
Al2O3 ≥
80
75
84
84
82
82
Compression strength Mpa
78.5
68.6
35
35
70
70
Apparent porosity %≤
19
18
17
17
19
19
Bulk density
2.95
2.95
2.93
2.93
2.88
2.85
Liner change rate (1500℃,3h)
/
/
0.4
0.4
0.4
0.4
With the development of electric arc furnace steel smelting technique, high power and ultra high power electric arc furnace steel making ratio is increasing, steel smelting tempo is speeding, electric arc furnace should endure more intense thermal radiation, thermal shock and dust action. Burned high alumina bricks can’t meet production requirement anymore, so, corundum castable and corundum precast block, chrome corundum castable and block, corundum magnesia castable and precast block are mainly used at electrodes triangle zone of EAF cover. Burned high alumina bricks or unburned high alumina bricks, magnesia bricks and magnesia chrome bricks are usually used at outer parts of furnace cover.
